RCU Forums - For the paint gurus

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RE: For the paint gurus

Interesting stuff SP.

Ever have a paint job that is turning out swell, turn south on you once you can't really fix it!?

I have been in the last throws of the finishing of a Tipo 720 and I was quite pleased with how the process was going. After a month of prep, prime, sand and paint (many times repeated...) as well as Monokote covering of wing and stab panels (wing center section is paint), I was ready to finally shoot my clear coat and so I did.

The CC is supposed to be crystal clear or water clear if you will and shouldn't add more than depth to the paint. In other words, white, primarily, should stay white. I always expect a little colour shift (after all, one has to account for the light dispersion of the clear enamel) or light bending, if you will but... My CC went on clear, dried fine and glossed up as expected without tinting. It has now cured for close to a week and as the days have passed with the fuse curing in the shop, the white has gradually, day by day, become more of cream colour and the clear coat has darkened the colours. Aside from the white there is no issue as all colours were shot with paint and so have cured to the same hue (including colour shot on the wing and stab panels - only way to achieve an identical match). The white, however, well, that's another story.

I am trying to take it in stride because there isn't much that can be done to get that clean white color of the paint back (other than starting from scratch - again), but it does aggravate the hell out of one. One expects a crystal clear product to be so and the amount of yellowing is quite pronounced. The white paint I had sourced was a pretty good match to the icy jet white Monokote so I was hoping for something reasonably close once cleared - not so...

At this point, the idea of going back to square one on the fuse makes little sense from all standpoints. I'll just have to be happy with the idea that the white I was aiming for will be a creamy white rather than a cool sharp white. However, the MK covering is another story. The only way I can see the model coming together in terms of white hue would be to strip the wing and stab (and rudder) from MK and paint them.

Before I consider doing that (which is not likely), does anyone have any magic tricks in order to bleach or clear up yellowish clear coats?

Dang, that is frustrating... [:@]

David.

P.S. Beware of acrylic enamel clear coats!

RE: For the paint gurus

Quote:

ORIGINAL: Roguedog

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

David,
Bummer! http://www.rcuniverse.com/forum/js/f.../cry_smile.gif
After reading your latest post I did a little investigating on what is called Epoxy Appliance Paint. Before I get to that I need to mention that in my previous post I wrongly listed Krylon as the product i used. The product I used was the Rustoleum brandof Epoxy Appliance paint. Both are Enamels but the Rustoleum brand takes way longer to dry and is where I got the info I quoted in my previous post.I forgot thatif you want a rattle can paint that drys fast you need to use the Krylonbrand.

I went to both websites and it turns out both companys are using the the term "Epoxy" very loosely. Both products are in fact a type of Enamel Paint andnot really Epoxy based at all as far as a thermosetting polymer.Normally, an epoxy paintis composed of two parts, a resin and a hardener. Not so with these so called Epoxy Appliance paints currently being marketed by both company's

Since these Epoxy paints are really enamels I think this may be the cause of the discoloration you experienced.

According to the link page above to the LustreKoat Clear page, Tower hobbies tech notes is claiming that LustreKote is an Acrylic Lacquer Paint not an Acrylic Enamel. If that's the case then here's what probably caused the discoloration. I believe lacquers over enamels are not compatiable thereby casuing the discoloration.

Using the chart the Paul posted in post 21, and using C = compatible and N for not compatible than according to thechart it shows N as far asusing lacquer over enamel.

At first I thought maybe the LustreKoat had blushed, like what happens when you try to use epoxy laminating resin when its to humid or cold. If that was the case you could have possibly wet sanded the offending clear coat off.

Did the other colors change hue? If not, this could bea solution as you could sand off the clear as best you can then recoat the white and touchup the other colors. PITA, I know but I have a feeling your not going to be satisfied unless it's right. Which probably means sanding off all the white and starting over. Bigger PITA.

Not that you would want too, but does Monokote have a matching creme color for the wings?

Bryan

RE: For the paint gurus

Bryan,

thanks for your comments and suggestions. I'll have to weigh my options.

I probably should have clarified in my previous post what paint I have been using. I used no Lustrekote paint or clear coat on any aspect of the finish of this model. I'll comment in line below to respond to some of your suggestions.

Quote:

ORIGINAL: Roguedog

David,
Bummer!
After reading your latest post I did a little investigating on what is called Epoxy Appliance Paint. Before I get to that I need to mention that in my previous post I wrongly listed Krylon as the product i used. The product I used was the Rustoleum brand of Epoxy Appliance paint. Both are Enamels but the Rustoleum brand takes way longer to dry and is where I got the info I quoted in my previous post. I forgot that if you want a rattle can paint that drys fast you need to use the Krylon brand.

Yup, I can see this being the case - Rustoleum paints seem to be, in general, much heavier in "oil" content compared to Krylon. The following are the appliance epoxy's that I was able to locate from Rustoleum and Krylon:

http://www.rustoleum.com/CBGProduct.asp?pid=101

http://krylon.com/products/appliance_epoxy_paints

http://krylon.com/ca/eng/products/ap..._epoxy_paints/

The last two are no doubt the same product just labeled differently depending on the market (in Canada products need to be bilingual). The white epoxy I used is that shown in the last link although the label on my cans is an older version. However, they all appear to have medium dry times of hours not days.

Quote:

ORIGINAL: Roguedog
I went to both websites and it turns out both company's are using the the term ''Epoxy'' very loosely. Both products are in fact a type of Enamel Paint and not really Epoxy based at all as far as a thermosetting polymer. Normally, an epoxy paint is composed of two parts, a resin and a hardener. Not so with these so called Epoxy Appliance paints currently being marketed by both company's

I agree, they are not true 2 part epoxy paints such as Klass Kote and the like. They are however one stage epoxy resin based paints meaning that they contain epoxy resins in them. This can be "felt" when shooting and give the paint a smooth silky, almost elastic, feel to the touch once wet sanded. These paints contain clear coats within the can as well so this must be sanded off first if one desires to re-coat or shoot other paints over top (which is what I did).

Quote:

ORIGINAL: Roguedog
Since these Epoxy paints are really enamels I think this may be the cause of the discoloration you experienced.

The change in colour of the base white is more of a tinting effect than a discoloration effect. At first I thought the issue might have been due to mixing different types of paint but I was careful to get the order and type right to avoid chemical incompatibilities - every step of the way was tested. After a little further reflection this morning, I'm sure it is not an appliance epoxy issue alone as the tinting is happening to all the paint - lacquer, epoxy, enamel and, yes,... Monokote too! The clear coat gave the same tinting effect over top white MK! In short, the CC used IS NOT crystal clear as it's supposed to be.

Quote:

ORIGINAL: Roguedog
According to the link page above to the LustreKoat Clear page, Tower hobbies tech notes is claiming that LustreKote is an Acrylic Lacquer Paint not an Acrylic Enamel. If that's the case then here's what probably caused the discoloration. I believe lacquers over enamels are not compatiable thereby casuing the discoloration.

Using the chart the Paul posted in post 21, and using C = compatible and N for not compatible than according to the chart it shows N as far as using lacquer over enamel.

Yup, I was aware that Lustrekote was acrylic lacquer but as mentioned above, I used no LK on this project. I did however use automotive Dupli-Color acrylic lacquer but this was for the trim colors. I wanted to test how the lacquer held up when shot directly over top both acrylic enamel (I was using a red enamel paint) as well as epoxy enamel (the appliance white). As it turns out, the lacquer does craze when shot directly over wet sanded acrylic enamel, as expected, but it doesn't over the epoxy enamel base white! But I didn't need to shoot lacquer over the red, I just wanted to see how it behaved. That was important to know as otherwise the trim color might have ended up being a mess. In any case, I shot all color trim with a base of primer underneath so all color pigment coats (white, red, blue and grey) are separated by layers of primer. In brief, the paint job turned out without issue and flattened very nicely while holding on well to the substrates. The paint job was great until the clear coat went on! :eek:

Quote:

ORIGINAL: Roguedog
Did the other colors change hue? If not, this could be a solution as you could sand off the clear as best you can then recoat the white and touchup the other colors. PITA, I know but I have a feeling your not going to be satisfied unless it's right. Which probably means sanding off all the white and starting over. Bigger PITA.

PITA is right - massive one too! The colors did change hue as mentioned in my post above but there is no issue with that as the end result is just one of deeper/richer colors - there was no attempt to color match MK to paint, I knew it wouldn't work so I painted all color I wante to match including the colors over top MK on the wings and stabs. The one thing I couldn't handle that way was the base white coat. The fuse had to be paint and the wings/stabs, well, didn't have to be MK but the idea was to cover them for lightness. The appliance white was a pretty good match (as you'll come to see from photos I'll get to post at some point) to MK Jet White which is the reason I chose to use it. I expected the white to be slightly affected by a subsequent clear coat but no more than how it is affected by the clear coat contained within the paint itself.

The problem is squarely with the tinting of the automotive DC acrylic enamel top clear coat which is not water clear as it is supposed to be but rather yellows with time. It goes on clear, stays clear for a while and then begins to yellow as the hours and days go by. It could be that I just got a bad/old batch of CC... [:'(]

Quote:

ORIGINAL: Roguedog
Not that you would want too, but does Monokote have a matching creme color for the wings?

Bryan

You know how that goes, takes a problem and likely makes it worse. There is cream MK but it wouldn't match the tinted white either... and I'd have to rip my perfectly good covered and painted wing and stab to recover with cream MK... as you say, not that I'd want to.

I think my only tangible option to recover the base white at this point is to sand the clear coat off - probably everywhere and see where it leaves the white hue. Hopefully, no touch up paint would be needed (although unlikely) and I could re-shoot with a proper, non tinting, clear coat - probably 2 stage urethane clear. If the CC did affect the white irreversibly, I'd have to sand further to expose primer layers in the white masked area and re-shoot the white...[:@] Of course, it doesn't help that I have color striping in the white base layer as well.

A good lesson was learned though, on the next project I'll stick to single system paint! :eek: I'm curious to find out how much better DC acrylic lacquer clear coat is compared to acrylic enamel CC (it costs over twice as much). If lacquer is used throughout on the project, there will be no compatibility issues in using a lacquer top CC. Of course, nothing says so far that it doesn't have that same tinting effect, after a few days. Or, I might just go to a compressor and Klass Kote or stick to expensive 2 stage urethane CC.

If anyone has any other good ideas or suggestions, please being em on! :D

David.

RE: For the paint gurus

David. Your post # 18, Duplicolor, same as Lustre-Coat ? Do you think compatible ?
Vince

RE: For the paint gurus

Vince,

I wouldn't mix Lustrekote with DC acrylic lacquer - here's why: LK, white a lacquer based paint, contains clear coat solids in it so it dries to a high lustre as the name suggests. The fact that one can also shoot LK clear overtop is probably just a "deepener" of the gloss and useful if one wants to do multiple trim colors where one needs to sand off the CC solids that come out of the color LK cans. Shooting LK color over top other LK might work without prior sanding but it likely would be rather heavy and not look great.

DC acrylic lacquer does not contain CC solids and shoots pure lacquer color pigments - at least the Pefect Match type (I haven't tried their generic lacquer colors but I suspect they are the same thing with a limited selection of colors and therefore a tad cheaper). In other words, the two types of paint, LK and DC, are not that much alike.

With that said, if you wanted to shoot LK white as a base coat for example, then sand off all the gloss solids off it, mask and shoot trim colors with DC using a primer layer underneath, it will probably work. However, I would do a test before and leave it sit for a couple of days, maybe put it out in the sun too, to see how the two types of paint react. Generally, provided one has a decent primer layer between the paint types, one can get away with even shooting lacquer over enamel but not highly recommended. The lacquer bonds to the primer layer which acts as a sealer between the under lying lacquer (if LK) or enamel (of some other paint) or epoxy.

Based on my current experience though (although it's merely a bad case of yellowing CC), I'd recommend to staying with single system paint. If you want to shoot DC trim colors, shoot DC throughout and you should be fine - straight forward automotive application. The only limiting factor is that you will need to CC the DC lacquer which can be done with either clear lacquer (also from DC) or with a 2 stage urethane clear. The latter is in theory the best, and most expensive, option.

Hope this helps, David.

RE: For the paint gurus

Quote:

ORIGINAL: RoguedogI went to both websites and it turns out both company's are using the term ''Epoxy'' very loosely. Both products are in fact a type of Enamel Paint and not really Epoxy based at all as far as a thermosetting polymer. Normally, epoxy paint is composed of two parts, a resin and a hardener. Not so with these so called Epoxy Appliance paints currently being marketed by both company's<o:p></o:p>

David,<o:p></o:p>I believe it’s import to post accurate info so as to not mislead any others who might peruse these threads so I think this issue about what is or is not an epoxy needs some clarification.<o:p></o:p>Here's the online American Heritage dictionary definition of an Epoxy and an Epoxide<o:p></o:p>ep·ox·y <v:shapetype id="_x0000_t75" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"> <v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id="_x0000_i1025" title="audio" o:button="t" alt="audio" type="#_x0000_t75" style="width: 12.75pt; height: 21pt"><v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/t/pron.jpg" src="file:///C:\temp\msohtml1\01\clip_image001.jpg"></v:imagedata></v:shape> (<v:shape id="_x0000_i1026" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/ibreve.gif" src="file:///C:\temp\msohtml1\01\clip_image003.gif"></v:imagedata></v:shape>-p<v:shape id="_x0000_i1027" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/obreve.gif" src="file:///C:\temp\msohtml1\01\clip_image004.gif"></v:imagedata></v:shape>k<v:shape id="_x0000_i1028" alt="" type="#_x0000_t75" style="width: 3pt; height: 16.5pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/prime.gif" src="file:///C:\temp\msohtml1\01\clip_image005.gif"></v:imagedata></v:shape>s<v:shape id="_x0000_i1029" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/emacr.gif" src="file:///C:\temp\msohtml1\01\clip_image006.gif"></v:imagedata></v:shape>) KEY

NOUN:
pl. ep·ox·ies

ep·ox·ide <v:shape id="_x0000_i1030" title="audio" o:button="t" alt="audio" type="#_x0000_t75" style="width: 9.75pt; height: 15.75pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/t/pron.jpg" src="file:///C:\temp\msohtml1\01\clip_image001.jpg"></v:imagedata></v:shape> (<v:shape id="_x0000_i1031" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/ebreve.gif" src="file:///C:\temp\msohtml1\01\clip_image007.gif"></v:imagedata></v:shape>-p<v:shape id="_x0000_i1032" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/obreve.gif" src="file:///C:\temp\msohtml1\01\clip_image004.gif"></v:imagedata></v:shape>k<v:shape id="_x0000_i1033" alt="" type="#_x0000_t75" style="width: 3pt; height: 16.5pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/prime.gif" src="file:///C:\temp\msohtml1\01\clip_image005.gif"></v:imagedata></v:shape>s<v:shape id="_x0000_i1034" alt="" type="#_x0000_t75" style="width: 4.5pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/imacr.gif" src="file:///C:\temp\msohtml1\01\clip_image008.gif"></v:imagedata></v:shape>d, <v:shape id="_x0000_i1035" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"><v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/ibreve.gif" src="file:///C:\temp\msohtml1\01\clip_image003.gif"></v:imagedata></v:shape>-p<v:shape id="_x0000_i1036" alt="" type="#_x0000_t75" style="width: 5.25pt; height: 11.25pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/obreve.gif" src="file:///C:\temp\msohtml1\01\clip_image004.gif"></v:imagedata></v:shape>k<v:shape id="_x0000_i1037" alt="" type="#_x0000_t75" style="width: 3pt; height: 16.5pt"> <v:imagedata o:href="http://l.yimg.com/a/i/edu/ref/ahd/s/prime.gif" src="file:///C:\temp\msohtml1\01\clip_image005.gif"></v:imagedata></v:shape>-) KEY

NOUN:
In both senses also called epoxy.

An epoxide is a ring-shaped organic compound or molecule that results from the combination of the two parts of resin and hardener. The other characteristic of an epoxy is the formation of heat while forming the ring-shaped organic compound. <o:p></o:p>You say-

Quote:

I agree, they are not true 2 part epoxy paints such as Klass Kote and the like. They are however one stage epoxy resin based paints meaning that they contain epoxy resins in them.

<o:p></o:p>The two brands of Appliance Epoxy paints we discuss here do not fall into the above category at all. <o:p></o:p>It does say on the Krylon website that they contain Epoxy Resins but after reviewing the MSDS sheet for the both Appliance paints the formulations are similar to their other line of paints respectively nothing referencing any of the main ingredients of epoxy like the resin Bisphenol-A type epoxy . I reviewed the MSDS sheets of both and they did not say anywhere that they contained a one stage or single stage Epoxy Resin.In fact they are claiming them to be Enamel paint.<o:p></o:p>Nor are there any warnings of any kind about a thermosetting re-action after being sprayed. If you want to say they form some type of polymer, I’ll agree to that but as far as a one stage epoxy resin I suspect the term Epoxy Resins is a marketing term only. Saying that they have epoxy resins sounds better than saying plastic resins. Also may really refer to the finish they exhibit, a plastic like epoxy finish, after they dry.<o:p></o:p>You said –

Quote:

This can be "felt" when shooting

<o:p></o:p>To say that its epoxy by the way it feels is nonsense. I agree to the fact that they are very user friendly as to how they are applied but to say you can feel its epoxy is absurd. I think the feeling you were getting was from breathing in too much of the paint fumes.<o:p></o:p>If you review the MSDS sheets for the Dupli-color Clear Top coat Spray paint you will see that there are several really nasty chemicals inside. The two I suspect caused your problem are Toluene and the Methyl ethyl ketone. Both are very strong solvents. As a matter of fact I’ve use MEK to melt the plastic together for evaporative cooler water distributors. Nasty stuff. I suspect it leached out some of the color of the so called Epoxy White (Enamel paint) pigments and distributed them into the clear coat.<o:p></o:p>You say –

Quote:

These paints contain clear coats within the can as well

<o:p></o:p>What? This is just nonsense as well. How can a paint can with color pigment in it also have a clear coat in it as well? Come on dude.<o:p></o:p>I realize that your ego is bruised because you asked for advice about mixing different types of paints together then chose not to follow the advice given. What’s the point of asking for advice if you’ve already made up your mind not to follow it. <o:p></o:p>There are two way’s to learn, 1. the easy way, ask for suggestions and then follow the advice given, or 2. the hard way, I’ll do it my way because I know best and suffer the consequences.<o:p></o:p>

RE: For the paint gurus

Bryan,

I'm sorry that my last couple of posts seem to have upset you. It seems like I manage to somehow do that for whatever reason. I hope you are not still upset about our exchange and difference of opinion on file formats. I apologized with the best of intentions on that subject if I offended you and hope you will accept that apology.

In my reply to your post I was just clarifying some points based on what I did and what I've observed and learned with this particular project. There were some comments you made to the effect of incompatible paint types and the use of Lustrekote and I just wanted to point out that there were no compatibility issues nor was Lustrekote used anywhere in this finish. If you read some of the posts I made earlier on, you'll see that I took great care to inquire and further research what types of paint were in what products and what type of paint could be used in combination with others. The paint job was successful thanks to everyone's advise and recommendations. The choice of final CC product used was actually not selected by myself but that is irrelevant. I agreed to use it and will therefore have to correct the problem it gave rise to.

As a final comment, I'll venture that there are other ways to learn beside the two that you state. With that said, if I had to select between the two options you provide, I'd probably select option 2, not because "I know best" (if I did, I wouldn't have started this thread), but because I believe that one learns best from one's own mistakes and not from the advise of others. Advise is simply that, recommendations based on the experience of others. Some of it is good, some not so much. In the end one has to draw one's own conclusions and do things the way one chooses based on various different factors.

I'll fix the plane and all will be well. I hope once it's done and sorted out your frustrations (as well as mine - after all, it is me who is building the model) will appease. I hope we can keep this thread in good spirits as it was until recently.

David.