MTK

Mavre, (Greek response)

Please see above. Panels are not fully finished yet (trim and clear). After the yellow base my panels weigh under 10 ounces each (280 & 278). It's a fair weight and about 3 ounces less than the foam cored counterpart.

these are typical weights for plastic film covered wings except not sure how large. Mine are larger than typical.

Built up panels, properly done, should be 3-4 ounces lighter and possibly more. Example I covered mine with carbon tissue and Esaki Japanese tissue. I wanted the carbon for its stiffness but Esaki alone would have been fine. Or silkspan alone. The extra 6-8 grams is worth it to me.

MAVROS

Very good weight

thanks

MTK

Pat,

I need your help. Would you please email me?

Thanks

MTK

Pat, I reviewd the HOK paint website, TPC Global. With so many choices it was confusing but also very informative. The thing that got my attention was the one part colors. Using catalyst for every color as I do today is a pita. I love the idea of a great paint that is single component that can be protected by a two part clear urethane. Reminds me of the no longer available DuPont lacquers I used 30 years ago. Cheap and easy.

Is the paint available in half pints? I'd buy a few colors today. The neons and metallics and pearls open up a whole mother world

Portlandflyer

Matt,

Yes the HOK line can be a bit intimidating. I tend to find Coast Airbrush web site a little easier to work with on HOK paints. The main difference between HOK and most other auto paint brands is HOK is pretty much all custom mixes. They have some basic colors, but the lid gets blown off when you work with their custom stuff.

If you go to the Coast site you will see two types of HOK paint. The first line is the original "Shimrin" line:

http://www.coastairbrush.com/categories.asp?cat=44

Here you will find the bread and butter of their line with many pre-mixed colors. On this paint job under Designer Pearls (PBC) I will be using Majik Blue Pearl, Black Pearl and Razberry II Pearl. These are absolutely gorgeous colors.

Under "Solid bases" I will be using BC25 black and BC26 white. I also will be using SG100 Intercoat clear. Here you will find other pre mixed basic colors that are non pearl.

The HOK line has expanded dramatically when they introduced the Shimrin 2 line.

http://www.coastairbrush.com/categories.asp?cat=745

This line has some basic colors under the HS Graphic Basis tab, but the lid is blown off when you get to the FX Karrier Bases. With the FX bases you mix what they call Effects Packs into them. You can mix and match the Effects packs to create tens of thousands of custom colors.

Now go to the HOK site

http://houseofkolor.com/kolors/

Now click on Karrier Basecoat. If you click on any of the Karrier Basecoat colors, you will see a bunch of different color variations. If you click on that color it will take you to a page that gives you the formula which will be a blend of one of their Effects Packs with that color Karrier Base.

I will be using a several different color formulas on this paint job.

It took me a while to figure the whole thing out, but once you get the basics of their line it makes sense.

Both Coast and TCP Global sell small quantities of the whole line.

BTW you want RU311 Reducer for normal painting conditions. Most of the line is reduced 50%.

Portlandflyer

I have the white base coat shot on the wings, stabs and rudder. On the areas that will be solid white and yellow I shoot to get full coverage. On areas that will receive red and blue may be a bit thin, but will have full coverage when they are shot.

At his stage, this is pretty much your last chance to fix any flaws. The old adage about painting is, "if you want to find your imperfections. just shoot a coat of base color". It's amazing how many hours you can spend going over every inch of the surface and think you have all the little blemishes fixed, until you shoot on a base coat. because the surface is so uniform, imperfections are magnified. A little microscopic dent now looks like a moon crater. I had a few little small dents in one wing that I never saw, but jumped out after the white base was shot. The other area I tend to get imperfections is on the edge caps of the ailerons and stabs.

This step takes just a few minutes to fill them with glazing putty and wet sand back. Trust me it makes a massive difference in your final finish, so don't skip it. After I sand back the putty, I just re-shoot those spots with white. That's another thing I love about HOK paint is the ability to repair spots on the fly. I just fog in a few coats over the putty and you can never see any edge buildup on the repair.

Portlandflyer

A little about spay gun set up and use.

As I said before, these things are nothing more than tools, but we need to use the best tool for the job at hand. I will tell you gun technology and ease of use has improved dramatically with the advent of the HVLP guns. By the way, HVLP stands for "high volume, low pressure".

I think confusion comes in on both sides of the name. A lot of people when they see "High Volume" they think it refers to the amount of paint delivered. What it actually refers to is "high volume" of air. In the older style guns, air pressure was the main component to setup, but with HVLP guns "volume" of air is the most important. Volume of air, refers to the amount of air required. rather than pressure (they are two distinct things). In a conventional gun if we run 30 PSI at the gun inlet, we will have about 30 PSI at the gun cap. In a HVLP gun we may have 30 PSI at the inlet, but only 10 PSI at the cap. This is a major distinction in how paint is delivered between the two types of guns. In short, the most significant difference we see is less paint going into the air (lost) with the a HVLP gun. HVLP guns are very efficient in paint delivery. One very important issue is having a compressor that can deliver enough volume of air for the HVLP gun we are using. Most full sized HVLP guns require a lot more volume of air than a small home compressor can deliver. Check the CFM (cubic feet per minute) rating of your gun as well as your compressor to see if you have enough air volume.

Also confusion comes about in the name "low pressure". As I mentioned above, in an HVLP gun, the amount of air at the cap is what the name refers to, not the inlet pressure. We may still need to run our HVLP gun at 30 or more PSI at the inlet, just like conventional guns. One thing that is very important on HPLV guns is not to exceed the inlet pressure for the design of the gun. In most cases, the inlet pressure is stamped on the side of the gun. It is also important to set our air pressure with the trigger pulled, after the pressure drops.

Another distinction is painting distance. With a conventional gun we may be painting 8 to 10 inches from the surface, but we may be down to as little as four inches with an HVLP gun. I think painting too far from our surface is a major mistake made with HVLP guns. Now keep in mind, every gun is going to have a proper working distance, based on the gun itself as well as setup. If we run more pressure, the working distance is going to increase and the other way around.

One great trick to determine the proper working distance for any given gun and setup is to pull the trigger for full air, but not to release any paint. Put your free hand in front of the gun and draw it toward the tip of the gun. At the point we hear a distinct difference in sound is the sweet spot (distance) that we will achieve the best paint atomization. At that distance the gun is producing the finest mist of paint. If we go further (greater distance from our surface) the paint mist will start to accumulate into larger drops. I have seen this in my own painting by staying too far away from the surface can result in a grainy texture to the surface. This shows up a lot in shooting primer.

One other area that is very important is tip and needle size in our gun. We can't effectively shoot all forms of paint with the same size tip and needle. As a general rule we want to shoot primers at around a 1.8 to 2.0 tip size. Most base coats can be shot with a 1.4 tip and clears at 1.3 to 1.4. Keep in mind, these tip sizes are for a full sized conventional gun. I personally use a small detail gun to shoot base coats. With this gun I run a tip size of 1.0 that works perfect for the HOK paints I shoot.

The bottom line is it all comes down to set up and experimentation. One thing to do t check your gun is to shoot it at a piece of cardboard or a box. It's better to have it wrong on the box instead of on your plane.

Portlandflyer

With the holidays, it looks like I won't have paint for awhile.....don't get me started on UPS. Why does it take only three days to have a plane on my doorstep from France that had to go through customs that is several thousand miles away and it takes seven to eight days for a box of paint from California that is 800 miles away!

OK, let's cover a few more basics while I wait for paint.

Let's go over the two main groups of paint.

The first is what is called "single stage". Single stage requires no clear to be shot on top. The clear is basically part of the paint.

The next group is usually known as "base coat, clear coat system" or "two stage". This system is used on virtually all factory automobiles that I know of since the late 80's. This system uses a color base with a clear coat shot on top. One reason they dominate the auto industry is due to UV protection. In a single stage paint, there are limits of how much UV protection can be built into the paint. The bottom line is two stage systems typically have a longer life expectancy versus single stage.

The question is "why would I use a two stage system when I could save time, money and maybe some weight and use a single stage paint"?

It all comes down to "reflection" versus "refraction". Those are two extremely important terms to describe how we view paint.

In a single stage paint, when the sun hits the surface, the gloss is "reflected" back to our eyes. You may say, "well of course it is", but there is an important aspect to be aware of. You see because the clear is basically the paint, the suns rays do not penetrate the gloss surface so all we see is the base color and a gloss reflection.

Conversely with a two stage system, the clear coat(s) are on top of the base coat. So when sun rays hit the surface, they are not immediately reflected back, rather they penetrate the clear coat and any transparent coats on top of the base and then exit the clear back to our eyes. Another way to think about it is the rays penetrate the clear, bounce around and then exit the clear. The term for this is "refraction".

Refraction is what gives us "depth" to a paint surface. When we use a transparent paint system, you can see that exceptional depth can be achieved as the sun rays penetrate the many layers of paint. The refractive property can actually be measured in what is called the "IOR' or Index of Refraction.

out2pasture

This is the best Christmas thread ever!!! I have my sample piece all painted. I glued some 1/16 balsa on a piece of 1/4 ply. I used old (all my stuff is really old) deft sanding sealer, and then elmers wood putty. Sanded with 200 grit. Then Silkspan using water based Minwax from a rusty can. I had some left over Krylon primer. It was too hard but I was able to sand it off. Then I used automotive sandable primer. I sanded that to 400 grit. Then two coats of krylon white. Not sanded. I’m just using left over stuff to get the technique down. In some light I can barely see a couple of micro- wrinkles from the silkspan. It’s the best paint job I ever did! I’m ready for the next step. How to handle paint ridges when I paint over the white. (Wet sand?) Painting a design and proper masking. And then clear spraying. I have no idea how to proceed.

Portlandflyer

Mike,

Outstanding. Welcome to the dark side! One thing I always do at every stage is level and check, level and check..on and on. If I see a little ridge,or blemish, I want to get rid of it now! One thing I find is sanding wet may not always be the best for the stage or issue we may have. I find taking those stubborn little ridges and high spots out are better done sanding dry with a heavier paper.....gezzz, now there's another subject I need to cover...see what you did!

I will cover all your questions along the way.

Pat

Portlandflyer

OK boys and girls I just got notification my paint is in Portland Oregon, which is about 15 miles from my house so that means UPS will be delivering it to me in about 4 days!

I sent Matt some additional info on House of Kolor paint that he thought I should share. It was in response to questions from Matt, so I kind of rambled on. Here it is:


The problem with HOK stuff is it's like a kid in a candy store. The downside with their stuff is the pigments are ground so incredibly small, you have to lay down a lot of coats with some of their colors to get full saturation, but you won't get a lot of film buildup. Keep in mind, you never want to spray HOK overly wet. You can get good coverage with two or three coats of most of the colors, but that's not how you want to shoot it. If you lay it on like most paints with a wet edge it can crack. I have never had that happen, but they tell you not to lay it on heavy. Their white can take a lot to hide stuff under under it, due to ultra fine pigments, but like I said, you won't get a high build and weight gain it just takes a lot and get spendy.


The hot thing they now have is their Primer Sealers that the car guys are using. It comes in several colors and what guys are doing is mixing it to get close to their base color so they don't have to shoot as much base to get good coverage and it keeps the cost down. I haven't tried it yet. It is a catalyzed product. It's supposed to cover really fast.


http://www.coastairbrush.com/products.asp?cat=746



The paint mask material I use is so good you won't need to seal it at all. I just shoot right over it and have never had it leak under. If I think I may get a little bleed I shoot a couple of coats of SG100 intercoat Klear with an airbrush just on the tape edge. SG100 is the same as all the other base paints with no pigment in it.


http://www.coastairbrush.com/products.asp?cat=51



I have never shot their metallic's as their pearls are so gorgeous in the sun. Their pearls look like silk...very subtle. You almost have to get close to them to see they are pearls due to ultra high ground pigments. I would think their metallic's are going to look like most companies pearls.


Their candy's are true candy's. They are a dye like water that you mix with SG100. They must be shot over a base coat and normally require several thin dust coats. They can be hard to shoot.


I buy white by the qt and of course always have black. Other than that, I never keep any of their stuff on hand as it's so expensive. I just lay out my colors and buy what I need as I go. The good thing is, I now have a pretty good amount of left over stuff. I was able to paint one of my Proteus with stuff I had on hand.


Base colors like the red and blue I will be using on this build cover pretty fast. Again I tend to have a thin base of white under them, so they cover pretty fast. The other thing interesting about their stuff is you can shoot them over a black base and have a much different color.


One other thing I find is the color samples they show on their site are shot in very bright light. They look too dark when you shoot them indoors, but look like the samples outside in the sun.

kenh3497

I too need to back up a step or two or three...

"You guys" are adding carbon veil to the skins then putting the tissue on top. Would there be any advantage to putting the carbon on the bottom of the skin next to the foam or rib as the case may be? Could the carbon be pre-glued to the skin and then attached to the ribs on a built up wing?

Thinking out loud here... the carbon being porous could be laid between the skin and foam on a foam core wing. I love the polyurethane glues for skin attachment. The PU glues should foam right through the carbon and bond everything. With the tissue on top this should be a supper strong skin.

Thank you

Ken

Portlandflyer

Ken,

I am personally not using carbon veil at all. Matt K had done it both ways. He has put it under the balsa skins on foam core wings and has also applied it on top of the balsa sheeting with silkspan applied over the carbon. He does this for strength from the carbon and the silkspan gives a smooth paintable surface.

Portlandflyer

With my comments to Mike, it got me thinking about just basic sanding skills. I'm old and when I was a kid building toy airplanes, pretty much anyone that built knew how to sand properly. Unfortunately, even that rudimentary skill is dying in our ARF world. I know this thread is about finish and painting, but if it ain't right on the bottom, it ain't going to be right on the top.

If I were to ask most anyone thinking of building a plane if they know how to sand, they would most likely all say "well of course I know how to sand". But do they really?

Here is a classic mistake in sanding we have all made (or you will). Let's glue on a leading edge to our wing and let it dry. We now come back with something like 220 or 320 grit paper and start to feather the leading edge into the balsa sheeting on the wing. We get all done and find we have one little spot about two or three inches that we can feel a little ridge, so what do we do?...we start sanding it more and more and more and of course it never gets any better in fact now it's getting worse! But I am doing everything right..I'm using a sanding block!

What we now have is a valley or low spot behind the leading edge. So what do we do in desperation? Yep we get out the light weight balsa filler and load in a bunch in that low spot. Of course we are not happy campers, so when it drys, we lay into the filler to sand it level with the leading edge and guess what boys we now have another dip on the back side of the filler where it meets the balsa skin...ahhhhh...Uncle!

So what's the deal. OK it all comes down to density of woods. Keep in mind our leading edge is going to be a totally different piece of wood than our skin material. In fact, I can pretty much guarantee it came out of a different tree. So here is what we did. We used......wait for it.....too light of a grit paper with too much pressure! But you are thinking, this guys nuts. If I used a heavy grit paper, it would make it worse! Nope. Other way around. You see what happened was you were using too light of a grit paper and applying way to much pressure to get the paper to do it's job and cut. So what happened was you were unknowingly applying excess pressure to the lighter density wood (the wing skin) so it just did what it was supposed to do and took off too much material.

So here is how we stop that...we use a heavy grit paper first with...wait for it...low pressure. In this case I would have leveled the leading edge with something like 80 grit. "80 grit paper" you say as you run around the room like Doc Brown did in Back to the Future...1.21 Gigawatts! That's right, very high grit paper on a sanding block with very very low pressure. What you do is almost skim the top surface just knocking down the higher (and higher density wood) leading edge. So now that we have it down nice and level what do we do to get out the 80 grit scratches? Well we don't go back to 320 because guess what, we are going to sand in the dip again...think about it. What we do is just go up gradually with the next paper grit like 120, then maybe 220 and then to maybe 320. When we go up in grit (finer) we only need just a very few passes to remove the prior grit scratches. Remember we have already leveled the surface so keep the pressure down on the block or you will be right back with the same problem.

One other cool thing about the Min Wax, silkspan system is you don't have to even mess with those ridges in the first place. I just leave them alone. You see when you apply the Min Wax and silkspan, pretty much all the wood becomes the same density...ding, ding, ding...is the bell going off? So now when you level the silkspan after it dries, all of those little high spots just disappear and you can do it with 220 paper. Cool!

Lesson over....you are excused.

MTK

Kenh,

you want use the .2 ounce carbon tissue. You can purchase at ACP or BrodK. A foam wing doesn't need the carbon. Silkspan alone has plenty of strength as does Esaki tissue. Buy them at Brodak too.....

A built up wing will have some distance between the ribs and the only reason I did mine with carbon and jap tissue was for the poke through strength. It just aggravating to grab a panel awkwardly and crack the balsa skin. If the spars are designed right, carbon is not needed for anything else. Still, as light as it is it's added insurance, enabling using ultra light wood on built up wings.

It's best to use the carbon inside the skin, as I described above. Problem I had was I thought I had the material and didn't. I waited almost 3weeks before it arrived and by then the first panel was done and I had the second started. So I compromised. The skins are tough just the same. I can lift the whole panel by the tip so this approach is fine for our purposes.

Your Choice.

Edit..... You don't want the heavier carbon. It's the same price and it's tempting but the heavier grade is much thicker. Thickness means weight and just because it sez 0.5 ounce doesn't mean that it's applied at that weight, it's not glass.

Portlandflyer

OK, let's start laying out the paint sequencing of the wings. Sequencing is just the steps taken to get the best job in the least amount of time. I will do the cool Tribal Graphic last, so you have to be patient grasshopper.

Now one thing I never do is butt two colors together. The problem when you do this is you now have two raised edges to deal with...one is bad enough. What I do is always paint a fraction of an inch back over the adjoining color to only have one paint ridge.

So take a look at the attached layout of the wing. You will see there will be a yellow band and yellow on the tips. One thing we always want to do if possible is paint dark colors over light colors. You will also notice multiple pinstripes that will all be in HOK Metalume that looks a lot like aluminum. Now this is the one thing a lot of uninitiated get totally wrong. Guys will look at a paint job with a bunch of colors and be impressed, when in fact the little details like pinstripes take way more time and have to be precise. Think about the fact that each edge of a pinstripe has to be masked and you can see the amount of time that goes into it.

There are several ways to lay it out and I may adjust on the fly. It should make sense as I go along.

Within the yellow band, there will be "Austral" ghost images embedded in it. A ghost image is there but you have to look close to see it. I also call them Easter eggs because you have to look hard to find them.

I couldn't find anything I liked for the Tribal Graphic in the center, so I drew it in Corel Draw. It probably didn't take anymore than thirty minutes to have it roughed out. You will see two additional lines in the graphic which will be used to paint a double bevel. More on this when I get there. This is the same one I used on a Proteus, but made some adjustments.

I'll probably do something pretty tricky on the Austral logo on the wings as well.

I will also have a surprise that I will be doing on the Tribal Graphic, but you just have to wait to find out!

brifly

Hey Guys, please add me to the list of lurkers. I've got an old Tiporare that I picked up cheap. The fuse was painted but it needs the runs sanded out of it, it's really a mess. I'm planning to sand all the paint off and then remove the Monokote from the wings. I like the idea of using the paper to cover the wings. I just read this entire thread from start to finish, good stuff. I originally thought of using solvent to remove the paint, but now I'm convinced to sand it out with a rough grit and working my way up with a light touch. See I did read it !

Portlandflyer

Tough call on the fuselage paint. It could be a massive amount of work to get it off by sanding...you need to hit it and see how it goes. You might be better off with some kind of stripper, fix all the stuff and re-sand. You may not have to get all the paint off the fuselage. You may be able to wet sand it with 220 to get it level. My experience with a lot of paints is they go on easy and come off hard. I wouldn't go to low in grit to start with...maybe 220. If that doesn't do it go to 120 and see if that works. You are not really trying to get a level surface at this point, just get all the old stuff off.

brifly

Hey Guys, please add me to the list of lurkers. I've got an old Tiporare that I picked up cheap. The fuse was painted but it needs the runs sanded out of it, it's really a mess. I'm planning to sand all the paint off and then remove the Monokote from the wings. I like the idea of using the paper to cover the wings. I just read this entire thread from start to finish, good stuff. I originally thought of using solvent to remove the paint, but now I'm convinced to sand it out with a rough grit and working my way up with a light touch. See I did read it !

brifly

I'll hit it with the 220 as you suggest first. I'm not sure how long it's been on there, maybe 10 years or more. Hey sorry for the above double post. I didn't think the first one posted. I'll catch on..

Brian

MTK

I agree with Pat. You may want to use a stripper. The paint on the classic is either epoxy or urethane. Both should respond to stripper reasonably well. Most likely the paint was not baked on. Many of today's planes that are painted in the mold are very hard to strip down to the glass with stripper because of the baking. And they are also hard to sand.

I would use wet or dry wet paper to keep loading to a minimum on the fuse.

Portlandflyer

A few more masking tips.

On the attached illustration you will see in Number 1 how two colors are painted next to each other (butted). We want to avoid this if at all possible as it will leave two paint ridges after the masking tape is removed. The big problem is when you do this it can leave a very ragged (uneven) edge after you knock back the ridges. The other problem is, both colors have to be aligned perfectly or you will get unwanted overlap or a microscopic gap between the two colors allowing the base color underneath to show. This can all be fixed, but it's very time consuming.

Number 2 shows the preferred method of masking by having the one color overlap the other by a very small amount. This will give us the cleanest line with only one paint ridge to knock down.

In Number 3 we see two arrows marked Correct and Wrong. To keep paint buildup at the edge of masking tape to a minimum, we want to shoot our paint at a right angle (90 degrees) versus shooting into the tape at an angle. This can make a major difference in the amount of paint buildup at the edge of the tape.

You can see in the attached picture a very small overlap of the silver pinstripe onto the adjoining purple paint on both sides. I prefer to shoot a dark color over the lighter color, but you can see it works fine both ways. Now this picture was taken before the clear was shot. After the clear is applied and cut back (leveled), you will never see or feel the slight overlap.

Portlandflyer

Blue Shift

"Blue shift" is a term used by artist. Blue shift is a problem that can arise when we shoot white over another color. Now if we shoot solid white against a darker color it will not be a problem. Where the problem can arise is when we blend (fog) white over another color. let's say we are doing some shading from red to white on the side of a fuselage. In other-words it starts out as solid red and turns into solid white. In this case if we start with a white base and then blend red back over the white we won't have an issue.

But let's do it the other way around. Let's say we shoot the red first and then start blending (shooting) white over the red to create the same blend. What can now happen is where the white is transitioning to the red, we can get a really ugly shift in the white towards blue. At the extreme, the white in those transition areas can turn to a muddy gray.

Here is the theory. If we just take a dot of white and put it over a red base and look very closely we may see a little bit of blue at the edges of the white. Now if we were painting a picture with oil paints it may not be an issue, but let's think about what happens when we use an air gun or airbrush. What happens in an airbrush or gun is the paint is broken into thousands of little tiny drops. So if we think about a blue halo around each one of those little dots, we can see how blue shift can occur.

The bottom line is the way to prevent it is to shoot the dark color over white, not the other way around. Airbrush artist sometimes mix a drop or two of orange into their paint to counteract it from happening. Remember Orange is on the opposite side of Blue on the color wheel.

cardinalflyer

My Feedback: (11)

Thanks for this thread! I have been painting r/c airplanes since the 60's and have been through a number of different systems. There are always new products and techniques to learn and I am getting an enormous amount of helpful information which I can use in my current projects. Keep up the good work for those interested in craftsmanship we truly appreciate the good advice.

Portlandflyer

Here is the before and after. You can see the overlap is not noticeable after the clear is shot and cut back.