For the paint gurus
 

I'm in the throws of finishing up a paint job. Thus far I have used a combination of different products including 3 different primers and at the moment have used two different kinds of paint with a third type of paint awaiting the next masking round.

To be a little more specific, the model was first primed with a dark Dupli-Color (DC) sandable primer. The model was filled with Bondo spot putty where required and the primer and Bondo wet sanded down. This was done in a couple of coats:

http://duplicolor.com/products/sandablePrimer/

I then proceeded with a DC polyester resin based high build primer - great stuff:

http://duplicolor.com/products/fillerPrimer/

This primer was also wet sanded down to smooth uniformity in a couple of thin coats. Some minor imperfections were spotted after the first coat of primer so more Bondo was used and wet sanded down with the primer. This particular primer leaves the surface akin to a baby's bum. Being gray, not having much texture and also being a polyester resin based primer I was a little concerned in how well an epoxy white base coat would adhere to it so I proceeded to shoot the model with Krylon white primer prior to shooting the white epoxy. Here are the two products used:

http://krylon.com/products/indooroutdoor_primer

http://krylon.com/products/appliance_epoxy_paints/

The base coat white was done in three coats wet sanding in between and turned out peachy. It wet sands very nicely and is very close match to MK Jet White. I let it dry for several days and I don't feel like there will be any issues with the epoxy white base coat. I would now like to do two things:

1) Shoot some trim colors with DC Perfect Match metallic paint which is an acrylic lacquer type paint:

http://duplicolor.com/products/perfectMatch/

2) Wet sand the whole fuse and apply DC Perfect Match clear coat.

Some concerns:

1) Will the metallic DC paint take to the epoxy white base coat or should I re-prime the surface prior to applying the DC?

2) I understand that metallic paint can't be successfully wet sanded without adversely affecting the texture. How does one go about clear coating metallic paint - does one just shoot without sanding? If so, is there anyway to even out the paint lines if one can't sand? Will clear coating actually change the texture as well? I want to think not as otherwise one could not achieve the result of the intended purpose of this paint - fixing areas that have been damaged in automotive applications.

3) Will there be issues if I shoot the DC clear atop the white epoxy base coat? Would it be preferable to use an epoxy enamel based clear instead of the automotive acrylic lacquer?

Any suggestions or recommendations are much appreciated.

I think next time I will just stick to one brand and/or system of paint - unfortunately I was unable to find DC white or red tones to suit my application.

TIA, David.

RE: For the paint gurus
 

I would test the metallic over the white krylon on a test panel. Auto paints tend to have strong solvents that melt most other paints. Primers tend to evaporate fast so they dont attack, but to get gloss the colors dry slower,eating what is under. I have had planes in all duplicolor but never mixed brands. also make a test for sanding; I have sanded real cars with metallic before clearing that looked like it should. Your just going to have to make a test panel.

RE: For the paint gurus
 

TFF,

thanks for the feedback. I have actually worked through test panels as I moved along testing each layer as I went. What I haven't done is tested wet sanding the metallic or seeing the results of clear over top. I held back on these stages as I wasn't there yet and wasn't sure what testing to actually do. I also wanted to test clearing atop colour coats and white base coat with the final clear - I'm not certain whether the DC automotive clear is the way to go thinking that epoxy based clear would be more durable and perhaps harder.

I have some experience with epoxy based paints but not much with automotive acrylic enamels such as DC so wasn't sure what to expect. Also, the fact that it is automotive means to me that it is gasoline proof but not necessarily nitro proof. How much stock should I put into that? Can automotive paint like DC be considered to be 20% nitro proof provided it is not poured on to the model in pure form... :)

David.

RE: For the paint gurus
 

sanding metallic with 1000 to 1500 grit should be fine, the clears will give back the gloss and depth, epoxy clears yellow , so you don want that, urethane clears are the way to go, they will hold up well with nitro, ppg clears will hold 90 percent nitro, i am using slik and quick clears from axis coatings, a quart plus hardener runs 30 us dollars, ad some medium reducer for another 8 dollars and you are good to go

RE: For the paint gurus
 

Lorin,

thanks for your suggestions. Are there any compatibility issues between urethane clears and the epoxy and acrylic lacquer paint coats? From what I've heard/read so far, the trick in avoiding crazing and other compatibility issues is to make sure all underlying layers are fully cured - make sense?

David.

RE: For the paint gurus
 

Lorin,

It seems like urethane clears apply over cured enamels and lacquers without a problem. I've been painting with cans in the absence of a compressor and found this stuff:

http://www.repaintsupply.com/pd_2_part_2k_aerosol.cfm

Looks promising, what do you think? Ingenious 2 part system in a can - never seen that before.

I also just found this interesting thread:

http://www.rcuniverse.com/forum/m_7591929/tm.htm

David.

RE: For the paint gurus
 

Don't use the epoxy paint. This is a single part epoxy that will not cure until the solvent evaporates, this takes a long time. Even then It is not really that good compared to a two part epoxy. Better to use the Duplicolor car paints, check the back of the canto make sure you are useing an acrylic lacquer. These are fuel proof to about 20% nitro.There are several products that are acrylic lacquer, the perfect match is probably the most common.

http://duplicolor.com/products/perfectMatch/

RE: For the paint gurus
 

David can you get this shipped to you?
These were the types of paint can product’s I was referring to in the other thread.

Spray max, U-pol, Transtar all trade names for can systems like this.

RE: For the paint gurus
 

Paul,

apparently yes. Unfortunately not from that particular supplier though which sells it ~$5 than Eastwood who will ship anywhere in Canada except for Alberta:

http://www.eastwood.com/spray-max-2k...t-aerosol.html

I'm just wondering if the extra cost and shipping for the urethane is worth it or whether I should just give the automotive DC acrylic lacquer a try - actually, shipping aside, they cost about the same amount. DC is available locally though so no shipping is required.

David.

RE: For the paint gurus
 

Are you guy's painting with this rattle can system, as pictured? I have had excellent result's with the TF Lustre-Coat. From the source's shown in these thread's, can I buy acrylic enamel ready to go with these spray can's, or whatever else that can be used, for up to 20% nitro ?

Thanks,

Viince

RE: For the paint gurus
 

David

I recently used the Krylon single stage Epoxy appliance paint and if I remember correctly you have initial short recoat time when applying the paint and then must wait several days (1 week?) before recoating with the same paint. Other wise it will cause blistering or ripples.

I would stick with the duplicolor and not mix them with krylon or other different paints.Could have unexpexted results later from the nitro fuel.

I also would recommend a Urethane clear that requires a hardener and believe that you can use the urethane over most painted surfaces. It is always best to test the paint you're going to use before applying any clear coat.

As a matter of fact you could probably use just about anything you want for base coat paints if using a Urethane plus hardener clear coat system.

As far as sanding tape lines from the different colorsI would lightly wet sand using1200 to 1600 grit wet to flatten anyraisededges of paint from doing a color scheme. The Clear Coat should produce a nice flat finish after the light sanding, even with a metallic base.

As far as nitro proof any two stage (clear with hardener) should provide a very tough surface (fuel proof).

You really need to invest in a compressor of some sort as what you're using for your projects sounds like a real PITA.

I got this setup from TCP Global for airbrusing.
http://www.ebay.com/itm/Badger-CRECE...item2eb6ec0b40

Comes with a Badger Crecendo airbrush, a really cool airbrush compressor with a one gallon storage tank for positive air pressure at the airbrush tip, a airbrushstand, a really cool cleaner jar forcleaning the airbrush, aset of Createx Paints, mixing utensils.

You have a choice of airbrush I believe and get an Iwata if you prefer.

Check out the Ebay TCP Global website and their regular website http://www.tcpglobal.com/as they have all the paint and painting tools that you could possible need. The Realistic Live Fire Flame kit is freaking way cool! http://cgi.ebay.com/ebaymotors/AUTO-...item2eb7581f7e

The Auto Air colors are a water based paint that's compatable with just about any Clear Coat system available and comes in pearl, metallic, transparent, Candy. etc

Bryan

RE: For the paint gurus
 

Vince the 1K cans from Spray Max can be used with Lacquers, Automotive basecoats and single stage Acrylic enamels, even waterborne basecoats.

My Local PPG rep custom mixes color match paint and can put it into one of these Spray Max cans.

Spray Max is not just the paint but the paint can system. I just happen to have a local source for this.

http://www.spraymax.de/index.php?id=443&L=1

You can get the same results as a high end spray gun setup.

RE: For the paint gurus
 

Thanks Paul.

RE: For the paint gurus
 

Guys,

thanks for the various feedback.

I'll comment a bit on my experience so far. My initial post might have been a little misleading as it may have come across as what my "plan" was for the finishing of the model - in fact, I am (was) already done with most of the products mentioned so some of your recommendations are well noted but, as it were, it is too late now - they have been used and, to the extent I have used them, seem to work well.

Initially I didn't want to mix brands or products as it is simply easier to use a single "system" who's compatibility is known. DC primers and paint would have worked but, as mentioned, I was unable to find a white I was pleased with in the five different automotive perfect match (auto brand specific) colours available. As a result, I proceeded to prep the model with automotive based primers and then did the basecoat with a one stage "appliance" epoxy based white which is actually very close to a covering white I wanted to match (MK Jet White). MK white has a "bluish" hue which makes it colder than most pre mixed (i.e., non matched) whites out there. This is understandable in that white's are more pleasing when slightly warmer but the colder MK hue provides better contrast with many of the other covering colours.

Relating my experience on the primers: first, DC primers were top quality - not like a two part catalyzed primer but much easier to apply (from an environmental conditions requirement) and probably less expensive. The base sanding primer provides a good layer for subsequent "adhesive" layers and sands at a very similar rate to fillers such as Bondo providing a classic smooth "mixed tone mess" for the second layer filler primer. This last primer is a polyester resin based primer which, like many who use polyester for glass work know, sands exceptionally well both wet and dry. Sanding wet is by far the preferable approach as it does tend to clog up sand paper but if an initial "cut down" of a particular area is needed due to some filler used, dry sanding is also an option. Of course dry sanding fillers such as Bondo produces a real mess so overall I did all 90% of all sanding wet - even if it might have taken a little longer.

Because the model was nicely prepped with the polyester filler primer I felt I could then proceed to try out the single stage epoxy based white. I was keen on trying it because it 1) offered a nice colour match and 2) because it was low cost (~$6 can I believe). But, again, since it is an epoxy resin based paint, I felt that it probably was not going to be a good idea to spray this directly over the smooth prepped polyester primer. As we know, polyesters over epoxies don't work that well (if at all) but the reverse works nicely. So I decided to shoot the polyester prep with an epoxy based "tack" primer in order to provide a surface for the white basecoat. The instructions on the appliance epoxy don't state that several days are required for it to flash and in fact, it dry's to the touch in 30 minutes (although I don't "touch"... [:-]) and cures in 24 hrs at 20 deg C. For peace of mind and to insure it was fully flashed, I waited 40-48 hrs between applications and wet sanding and applied the basecoat in three sessions. I was very pleased with the coverage and the results but it takes a little more effort than if one was using a urethane or an enamel. I'd say it compares in some respects with water borne paint except is has a higher solids content and of course, if flowed on, dries to a reasonable gloss level. The only issue with this paint, as can be expected, is that the hard gloss solids must be sanded down if one is to recoat otherwise the subsequent layers won't adhere - common sense. There is however no need to wait 7 days between coats and after 1-2 days of curing post wet sanding there is barely a detectable epoxy odour to the surface - nice. One of the strengths of epoxy based paint - low odour.

In short, I was and am quite pleased with the results of the epoxy white as a basecoat. I have since applied one layer of trim colour which comes out of a "third brand" product called "Rust Check". I believe this is a Canadian brand products but similar oil based "rust proof" enamels exist under other brand names in the US. I have been using light coats of white Krylon primer under each base coat layer including the red "Rust Check" trim which I shot a few days ago. It has proved to be a good foundation for color adhesion. The red paint is not an epoxy based paint and goes on quite nicely straight out of a regular tipped can (if memory serves) - no major splats or runs. It is quite tolerant of re-coating without running being relatively viscous and builds up quite quickly. I have now used it in three different areas and it took a single application to achieve a consistent pigment colour that held up well to fairly vigorous wet sanding needed to cut down the high gloss it leaves behind and to smooth out the paint boundaries.

I am not nearing the metallic paint phase of the project and as mentioned in my first post I was (still need to do a couple more tests) somewhat concerned about the viability of an acrylic lacquer atop an epoxy basecoat. In retrospect I don't think this will be a problem as acrylic's are pretty tolerant provided the surface is fully flashed. On the other hand, the concern of course has more to do with the "lacquer" part of the equation which implies mixing of solvents which may not be compatible but I'm quite optimistic. If it can be shot atop polyester resin based primers I'm doubtful that it would have problems on top of an epoxy based layer. Still, for safety and adhesion the underlying surface will be lightly primed with what I'm beginning to think of as a "universal primer" - the Krylon white.

Despite the apparent myriad of products discussed and, to some extent, applied to the model, weight gain has been surpisingly low. I was interested in seeing what particular product would have the most significant impact and so far it is the polyester resin based filler primer which, having filling properties, has the highest particulate density so far. The white epoxy and red enamel do add their share of weight but the majority of it is contained in their flowing gloss structures which, after being sanded down, actually loose a great deal of their mass. In the end, I suspect it will be the filler primer and the final clear top coats that will incrementally add the most weight. For this reason I have been quite emphatic with wet sanding every layer between coats.

We will see what milage I get from the metallic layers and how they respond to 1500 grit sanding. I will go much lighter on those layers even though I'm not that particularly interested in their metallic texture - it is more about their hue. I believe they can be dulled to a nasty look though if over sanded or otherwise exposed to water prior to fully flashing.

For the next project I may look into a compressor system (thanks for the suggestions Bryan) as I'm keen on using water borne products such as Auto Air as far as possible including glassing with products such as Minwax Polycrilic. Not as hard or fast as finishing epoxy but healthier in the long run and less critical in application - one can practically slosh that stuff on without ill result... [8D]

So that's the progress report. Once again, thanks for all your input - it is being stored for future projects and or used for this one. I may well go with the 2K Spray Max urethane clear for the final touch.

Whew! That was long.

David.

RE: For the paint gurus
 

Given the inclement weather due to tropical storm Lee, I decided to finish up some paint tests prior to shooting what I hope will be the last day of basecoat trim.

I've been doing some reading along with the testing and they each seem to confirm eachother:

At present I have a hybrid of paint types on the model but so far I have had no issues. In a nutshell, the single stage epoxy based white basecoat went atop the prior primer coat without issue. This last primer coat acted as a barrier to the underlying high build polyester based primer which was fully cured and wet sanded for several days. The basecoat seems to be stable after several days of having shot it and wet sanded it.

Atop I laid a trim coat of what I believe to be an acrylic enamel based paint. Again, with the base primer between the base white epoxy and the red enamel, there were no issues with compatibility. I am now at the stage where I will be using acrylic lacquer and this was the type of paint I was most concerned with. After my tests I discovered the following:
[ul][*] acrylic lacquer directly over cured epoxy holds.[*] acrylic lacquer over primed cured epoxy appears to hold very well.[*] acrylic lacquer directly over cured enamel does not hold (crazing and dullness result in the metallic lacquer).[*] acrylic lacquer over primed cured enamel holds but not exceptionally well.[*] acrylic lacquer over un-primed smooth substrate does not hold very well. This is probably true of most paints.
[/ul]
I have not done any tests with the clear coat process as I am in still in the process of deciphering what exactly constitutes Dupli-Color Perfect Match clear coat. I believe it to be a single stage (well, this part is clear) acrylic enamel (unless it is a lacquer like the matching paint) and it is in theory chemical resistant. It is likely no where close in hardness and durability to a two stage (2K) acrylic urethane but if I'm unable to source the 2K Spraymax urethane I might have to go with the 1K clear from Dupli-Color. It is likely higher in VOC's (lacquers are fast drying) so it should dry to a lighter (in terms of weight) finish compared to the high solids urethane. This, in turn, means that more coats will have to be applied to produce a hard durable surface. I'm thinking that 4 coats might be a good initial coverage followed by reapplication if needed after wet sanding.

Just posting these thoughts for future reference and in case they may be of some interest to others.

Attached is also a useful PDF from Dupli-Color with various painting tips.

David.

RE: For the paint gurus
 

Very useful information David. Your efforts are appreciated.

RE: For the paint gurus
 

The internet, as always, is a wonderful source of information - provided one has a bit of luck researching.

In my quest to better understand the various chemistries and "combined name" paint formulations (e.g., acrylic lacquer, acrylic enamel, alkyd (synthetic) enamel, polyester urethane (polyurethane), acrylic urethane, etc.), I have come across a very insightful summary on what has been traditionally used in the automotive industry over the last century. Here it is:

WHAT TYPE OF PAINTS ARE USED ON AUTOMOBILES?

Japanese Varnish: In the early years, between 1900 and the 1920's, Japanese varnishes were used. The varnish was applied by brush.

Nitrocellulose Lacquer: In the 1920's, several paint manufacturers were involved in the development of nitrocellulose lacquers. This paint had rapid drying and low viscosity properties, and was applied with air pressure through a spray gun leaving a hard dry finish in approximately one hour. When rubbed, polished, and waxed, it far surpassed in durability and appearance the qualities of the Japanese lacquers.

Synthetic Enamel: In the mid 1930's, a new and completely different type of paint was developed, the alkyd or synthetic enamels. It proved to have superior qualities in film strength, adhesion, luster, flexibility and durability over all previous paints. The resin base was developed from the reaction between phthalic anhydride and glycerin, with gums, oils and plasticizers added during the manufacturing process a drying oil such as linseed, a polyhydric alcohol, such as glycerine, and a dibasic acid, such as Phthalic Anhydride. It dries by solvent evaporation, like the lacquer paints, but the resin remains soft and sticky when no solvents are present. It cures to a hard finish by absorption of oxygen from the air. The curing process can be accelerated by heat, and several methods of baking enamel were developed. Unlike lacquer, when dry, it needs no polishing to produce a high luster finish.

Acrylic Lacquer: As time passed, chemists developed a substitute for nitrocellulose lacquer, using an acrylic resin as a base. The resins used in acrylic lacquer tend to be slightly brittle. This deficiency is overcome by the use of a plasticizer ( a liquid that is a solvent for these resins and softens them slightly). A cellulosic resin is any resin derived from cellulose (pure cotton). Acrylic lacquer was used extensively by General Motors.

Acrylic Enamel: During the late 1960's and early 1970's, technology brought on the development of acrylic enamel, which was harder and more durable. Chemically, it is a cousin to synthetic enamel, but is modified with acrylic resin, and is not soft and sticky with no solvents present. It cures further with the absorption of oxygen from the air. Unlike the lacquers, which remain soluble in solvents, the enamel family is insoluble in solvent when cured. An acrylic resin is chemically any polymer whose basic monomers are chemical derivatives of acrylic acid.

Polyurethane Enamel: In the mid 1970's, polyurethane enamel was developed to withstand the severe stress of high speed airplane surfaces, which are subject to rapid temperature changes and flexing. This paint was much more durable than the acrylic enamels.

Acrylic Urethane Enamel: Acrylic urethane enamels were developed to withstand environmental elements, such as acid rain and ultra violet rays. It is the most durable paint to date.

David.

RE: For the paint gurus
 

Further to the comment I made above, I have sorted out the Perfect Match CC enigma. It is not an acrylic enamel after all, but is instead acrylic lacquer just like the basecoat paint. Dupli-Color also produces a less extensive color selection automotive line of acrylic enamel paint which is in principle a tougher BC/CC paint system than the acrylic lacquer.

Here are the respective web pages:

General Enamel: http://www.duplicolor.com/products/premiumEnamel

General Lacquer: http://www.duplicolor.com/products/premiumLacquer

Perfect Match Lacquer: http://www.duplicolor.com/products/perfectMatch

This last is probably the same formulation as the general lacquer but has a wide variety of colors that are pigment matched to car manufacturer's colours. Given the fact that acrylic lacquer remains "solvent" (i.e., can be removed with an adequate amount of the proper chemical), I am surprised that this is actually the same type of paint as Top Flite Lustrekote. The "solvability" of lacquer is of course what allows it to be polished and buffed to a high shine but at the same time I'm surprised that it is not more sensitive to nitro. Perhaps lacquer withstands nitro up to typical "sport" fuel percentages (up to 15%) but not at higher "competition" percentages (30%). I take it urethane is likely impervious to 100% nitro when fully cured (weeks).

BTW, do you guys already know all this stuff? Maybe this is of little interest except to yours truly. In any case, it will be good to have it for future reference. I tend to forget all these details.

David.

RE: For the paint gurus
 

David,
Thanks for the research.
Do you have any idea how these do over sig nitrate dope, or anyother brand? I use the dope to stick sig coverall fabric because it is easy to remove and restreach just by brushing on some thinner.

Jerry

RE: For the paint gurus
 

Jerry,

there have been a lot of products and different types of paint mentioned above. Is there a specific type of paint or clear coat that you are interested in putting over nitrate dope?

As a general rule, acrylic lacquer will not like to go over anything other than a stable compatible primer or other lacquer. However, after revising Paul's table below, it appears that one could in principle shoot it directly over nitrate dope. In practice, I see no reason why one would want to do that as painting an unprimed model won't yield very good results. If one wanted to paint with acrylic lacquer over top nitrate dope, I would make sure there is a good primer sealer as a coat between the two. A primer sealer insures that the paint shot over top won't "eat" through the underlying layers but chemically bond only with that primer layer. Automotive paint is often acrylic lacquer so sealing primers are also well known and often used/recommended in the industry - at least that's the impression I have so far.

acrylic or alkyl Enamel is more flexible and will go over lacquer or enamel. Acrylic and alkyl enamels shouldn't be mixed but I would generally stay away from alkyl enamels as they are not as friendly or tough as acrylic enamels. Modern day enamels I believe are by enlarge made with acrylic resins - certainly the automotive paints. Alternatively they are epoxy based enamels. Finally, acrylic urethanes can go practically over any cured substrate provided it is clean and grease/wax free.

The dope that one has to watch out for is butyrate as it off gasses for a long time possibly lifting other coat applied over top. But then again, butyrate is often used as a finishing paint so it can be used as a single system. I'm not sure what's in Stixit or Balsarite type of "sealers" but I believe they behave in much the same way as nitrate dope in terms of what can go over them once cured.

I hope this helps, David.

RE: For the paint gurus
 

This should Help

RE: For the paint gurus
 

Paul,

that's an excellent chart! It just took me four weeks to arrive at some of those conclusions... :eek:

I'll have to check whether my conclusions are in agreement with it. Otherwise I'll have to rewrite all my comments! [:-]

Oops! Just did.

The interesting thing about that table is that due to its vintage, acrylic urethane enamels are not listed. At the time the table was compiled, they probably didn't exist yet! In any case, they would reside at the top of the sheet being the most stable and generally compatible finishes. I suspect they behave in much the same way as polyurethanes (currently at the top) with the exception that they might be able to go over top acrylic and possibly alkyd enamels as well unlike polyurethanes (per the table).

David.

RE: For the paint gurus
 

Acrylic lacquer is not completly nitro proof. However, it is just as fuel proof as butyrate dope, that is about 24%, but long exposure to lower percentages can soften the paint. Nitro really isn't a real strong solvent, it just happens to bother certain paints. Acetone, and MEK are much wors and there will sometimes be 5% of acetone in your fuel. I think acrylic enamal may be as or more fuel proof, but it has to be fully cured, and that may take longer than you think, thus if you don't wait enough say a week later it may not becured enough for nitro. I think there is a tendency for the cheaper acrylic enamals to be mixed with other paints such as alkyd enamel. There is also the same problem with latex, industeral and aviation latex is much more durable than most house paints because it is 100% latex.

RE: For the paint gurus
 

Splashing 10 percent nitro on your lacquer or dope finish will put white spots on it, no doubt. The fuel residue out of the exhaust is not a problem as long as one wipes the model down well and cleans it with some detergent and waxes it periodically. I've got some really old dope, and lacquer models with little to no staining, by being careful.
Chris...

RE: For the paint gurus
 

I have to admit I was rather surprised to learn that paints such as Lustrekote are acrylic lacquer based paints. My impression of lacquer is that it wouldn't be very durable in the absence of a clear coat. Heck, one can wet sand it to "leak" the pigments with nothing other than cold water!

I'd be a little weary of having a glow or gas engine model painted with lacquer without a chemical resistant top coat.

But kudos to you Chris for keeping those models free from the effects of fuel!

David.

RE: For the paint gurus
 

I have had had a few dope and acrylic laquer models and have never had lasting stains from raw fuel. Pretty sure I have spilt at least up to 15% on them. If you wipe the fuel off right away there is no problem. But if you let it sit for a while they may soften up the paint ,if you don't touch it it will harden back up, no spots but any gloss will be slightly duller. Wait a day or two and a bit of pollishing compound will take care of that.

RE: For the paint gurus
 

If this is what I think you are saying you may not be letting the paint dry enough before sanding.  If fully dry you will only have a dry powder from the laquer that will not bleed the color.  If the paint has a retarder it could take as much as a week to dry that much.  But most spray can laquers only have enough retarder to prevent moisture from fogging in average humidity, this causes the paint to discolor.

RE: For the paint gurus
 

I have a great background using paint products.

Pointless to respond though, because no matter what you say, there's always another way and a better one, AND with different recommended products. And they can all work! Well, not all.

So, I'll cut to the chase. I scratch built and painted this model in the 80's and it took Best Finish at the WRAM Show, back then.

Here's the product list .

Polyester resin over glass cloth.
Dupont two stage primer.
Dupont automotive paints and Dupont Centari clear.
One Shot lettering enamel.
30 minute Gold Leaf Size.
23K Gold Leaf
Dan's brushing lacquers. (NLA)

RE: For the paint gurus
 

Charles,

I have seen that model in other threads - very nicely done! It's too bad the pictures probably don't do it justice due to their age or scan quality. Still, one can see the effort and work that went into it.

This thread is to discuss paint and all comments on different approaches and techniques used currently and in the past are welcome. It's not intended to be a "one up, look at mine" kind of thread. That would be pointless. With that said, it is nice to show off our work so pictures are more than welcome.

David.

RE: For the paint gurus
 

The Duplicolor automotive acrylic lacquer I've been using has a re-coat time of 10 minutes and a "full cure" time of 30 minutes in prescribed weather conditions. One can clear coat this paint after 30 minutes. One can literally see the solvents evaporate as the paint dries. After 15 minutes, the paint is hard, dry and yes, "dusty" to the touch. With lots of humidity it takes a little longer but not significantly.

The area that was painted with lacquer was allowed to cure for over a week at 20 deg C and 50% humidity (my shop). I don't think that paint would cure any longer even after 24 hours but to be absolutely sure I left it anyway while working on other aspects. Even so, when wet sanded with 1500 grit, the paint will leak. In fact, this is the case with all the paint I used including epoxy enamel and acrylic enamel. After cutting throught the top gloss coats of the enamel, the wet sanding evidently cuts into the colour pigments and it will leak color into the sandpaper and water bowl. It just makes sense. If there is no color in the water, then one isn't sanding color paint pigments but rather clear coat layers.

In any event, the beauty of the wet sanding is the smooth silky feel it leaves allowing subsequent layers of paint to flow on equally smoothly. Of course, one then has to provide "grip" (i.e., primer) for some of it but it does build up nicely.

I doubt any lacquer would take upwards of a week to dry, it's just not chemically engineered to do so. Of course, if there is a lot of retarder in it as you mention or otherwise has clear coat pigments blended into the lacquer recipe, that's another story. Hard clear coats take much longer to cure than straight lacquer.

Paint such as Lustrekote (and I only keep referring back to it because it's a well known paint due to it's MK covering match) which is acrylic lacquer based has other clear coat chemicals in it to dry to a "thick" glossy finish. If one were to sand through those top coats though, no doubt this paint would leak too. In fact, I know it does as I tried it on a test board a week ago or so.

But the "leaking" is not an issue. When wet sanding, provided one hasn't allowed the leaked paint to re-settle on to the model for too long, it will wipe right off with a clean damp rag. I found that using warm soapy water is nice on the painted surface while cool water is preferable on primed surfaces. The model can then be wiped down with denatured alcohol for a chemical and grease free surface for final graphics and top clear coat.

David.

RE: For the paint gurus
 

The color you see on the sandpaper is from the removal of paint as you sand the surface. It "powders." Splashing it around in the bucket, washes the sandpaper clean. Repeat the process. Water turns the color of the paint. Eventually change the water.

Squeegee the painted surface, as you sand, from time to time, shows the highs and lows. I.e. "orange peel." The sanding eliminates this. Goal is to get it smooth.

RE: For the paint gurus
 

Charles,

understood and agree. Perhaps it's a question of semantics. What I was referring to as "pigment leaking", you guys are referring to as "powdering". I used leak as a term because water is involved and the color pigments are transferred to the sandpaper and bucket. But I see how the term powdering might be more appropriate as a powder is indeed what is left behind on the surface if allowed to dry and also what settles down in the bucket given enough time.

By the way, on re-reading my comment regarding your post, I can see that it might be understood in a negative way. What I was inviting you to do was to go ahead and post any comments or techniques you thought relevant in light of your sentence which began "Pointless to respond though, because no matter what you say,..." In other words, please do respond! In reality, this thread began with questions on my part regarding the compatibility of different types of paint as I was and still am in the process of finishing a model. This particular model was mixing a variety of different paint types and I was concerned with problems laying one over another.

At this point, the thread has served its purpose well thanks to the contributors and I have posted some of my recent findings in the finish process. However, I'd like the thread to continue discussing these topics further because, as you say, there are always other methods to finish that work well or better than what one is doing. I feel it is an interesting topic to us classic builders in general as we take the time and strive to finish our models in the best way possible.

Bring on more paint comments and techniques!

David.

RE: For the paint gurus
 

Lacquer doesn't cure it dries.  Not only that but if it dries till it cracks and flakes.  That takes a number of years depending on the amount of retarder and plasticisers.  The plasticisers are usually an oil that also dries out over time. 

RE: For the paint gurus
 

Hi,

So what paint is best to use if one want itto last many many years without develop cracks, flakes etc? I suppose polyuretane based paint (1- or 2-component) is a strong candidate. I was thinking of for exampleEd Kazmirski's personal Orion and Taurus that is in AMA museum - as far as I have seen they seems to be in very good shape even today. Was he using polyuretane paint?
Another example I know about is a gentlemen here in Sweden that has a 55 year old contest line control model that was painted in polyuretane paint and the model is still today basically in same good paint conditionas it was when it was new.

/Bo

RE: For the paint gurus
 

I've mentioned a few times the sandpaper I found (MicroMesh). It is a great product and goes way beyond 1500 grit. Glass smooth finishes are possible following their technique.

RE: For the paint gurus
 

Bo,

good question. In theory, the caliber of paint increases with more recently engineered paints. Referring back to post #17:

http://www.rcuniverse.com/forum/fb.asp?m=10705905

starting with Japanese lacquer (and probably dope's as well) and progressing up to the more recent acrylic urethanes, the quality and durability of the paint should increase. Polyurethane paint is very good and it is what I remember using as a kid to fuel proof anything that needed it. In those days acrylic urethanes didn't exist yet. I think they were developed in the last 20-30 years (maybe more recently). So, when possible, I'd be inclined to using acrylic urethanes. I believe they are also less toxic and have less of a smell. Anything that is polyester based (i.e., polyester urethane = polyurethane) has a strong odor and if you are sensitive, can give you a massive headache.

On the other hand, in the interest of longevity (ours, not the models :)), we'd probably be better off using water based products including water based acrylic paints as well as water based varnishes from MinWax and Varathane (you probably have different brands in Sweden) for applying glass cloth. Once finished, the nice thing about using water based paint is that the layers can be very thin and wet sanding to flatten the paint is probably not required. As a final fuel proof coat, one could then apply a 2 stage acrylic urethane clear coat, if the model has an engine and acrylic enamel clear coat if the model has a motor (i.e., electric).

I suspect that Ed's models were painted in silk and dope as was probably the convention back in his day. It's possible that the model might have been re-finished, perhaps just the top coat, since it's original paint job. It would be interesting to find out from the AMA what their understanding is of how the model was finished.

So what's on the paint roster Bo? [8D]

David.

RE: For the paint gurus
 

David,

I'll have to try that, thanks. I haven't forgotten your post just seizing the moment since the weather promises only a few more days of 20 degree weather up here!

1500 grit works pretty well for flattening the paint. I have also sourced some 2000 grit for the clear coat. I'm considering shooting clear, sanding and re-shooting a week later if weather permits. The final coat will be 2000 wet sanded and polished back up. I'm tentatively planning to use a product like Nu Finish but we'll see how it performs on the CC. I'll be trying it on a test board.

David.

RE: For the paint gurus
 

SP,

I realize there is no curing with respect to lacquer. That's why I mentioned that one could see it dry in real time. Very high VOC content. My reference to curing was with respect to the clear coat ingredients mixed in with lacquer in certain rattle can paints such as Lustrekote. Lustrekote does require time to, first dry (the pigments are acrylic lacquer based), and then cure (the CC is not lacquer). How exactly this paint is formulated is a bit of a mystery (there is no information on the TF site, a little on Tower's site) but I know it requires time to cure.

There was some confusion regarding my use of the word leak. Your use of the word powder is probably more appropriate.

David.

RE: For the paint gurus
 

Hi David,
If You promise to not laugh when You read this... Not an airplane this time but these two "vintage" things... One Wik "Helix" autogyro and one Hegi "Bell Huey Cobra". At least the Helix need a repaint as You can see. It is a cracy projects that I will do now since I always wanted to try that Helix since I first saw it in Wik catalog at about 1975. I had to search long before I found it. I have not decided if the Cobra will be repainted - it is rather rare, it is from 1973 and it was competing in first helicopter competition here in Sweden October 28 1973 and it placed 2nd out of 13 participants so It is probably one of the oldest helis here in my country. But my next airplane paint job will probably be a Mach 1 for my Pro Line radio that I plan to get airborne (need to get it converted to 2.4 GHz first). Last time I painted a Mach 1 (in 1977 - the last picture belowis that Mach 1, mine) it was painted in 2-component polyurethane, hand painted - we had no good spray guns back in those days (we had one spray gunbut it wasnot good enough for spraying our precious pattern planes with).

/Bo

RE: For the paint gurus
 

According to tower the CC is a lacquer.

http://www3.towerhobbies.com/cgi-bin...XCZW5&P=ML

The clear coat may have more retarder than the pigmented paints.The faster drying solvents dry first, once it is touch dry it takes much longerto dry enough to sand. Ihave addedenough retarders to make it take aday before you can sand,but it didn't blush! Acrylic plastic is the same plastic used in pexiglass and lacquer paints are basically this plastic disolved with solvents. The pigments are colored compounds, many of the same ones are used in all paints.