Paint for Foam Models

Kim, I use this https://www.systemthree.com/products/wr-lpu-polyurethane-topcoat   I use this for wood, synthetic coverings, etc. I love it. I purchase the 4 oz. samples and mix as needed.  It took me quite a while to learn how to use it however. It seems expensive, but when compared to traditional dope finishes and longevity, it's well worth it. It really is a learning experience. It goes over ANY water based product. It doesn't go over solvent based paints. Goes on like water colors looking like crap but after a few coats 3-5, it looks great. I use the clear as a top coat, not necessary but offers a lot of depth and I polish the clear out. When I use on wood I use nitrate dope . It will not adhere to butyrate dope. I use the nitrate because I prefer a solvent based product over a water based product on direct wood. When properly used on wood, you wouldn't be able to tell if it's paint or iron on covering if you desired it to be that way. Clear coats though would take essentially minutes and would offer nitro protection up to 45% using the crosslinker. When crosslinker isn't used, the paint will accept 10% raw fuel directly on it. I use the colors straight out of the bottle mixed with water and add the crosslinker to my clear coats.

Everything you know about painting goes out the window when using this product. It doesn't have to be dry for recoat, it also likes humid or damp days. Your also flying the model in the same day. You throw more material out then you use until you get used to it. The cross linker is a must and once mixed with the color, it can't be returned to the virgin bottle. If the material starts to pull a bit during application, a drip or two of cross linker re activates the material. This material dries through evaporation and a chemical reaction. Coats need to be done within 8 hours of each other or the following coat will not link onto it and will shed off. For colors I generally recoat as soon as it appears dry which is within 15 mins of each coat. I like to take my time with the clear a bit as this is what offers the shine and depth of the models appearance. I wet sand those coats.

        The colors mix wonderfully but you could use any latex paint and top coat with the clear poly so essentially all you need is the clear poly.  Powder can be mixed with the clear as a flattening agent if WWII colors are desired. I've sprayed the clear from Preval throw away sprayers. You could also contact Phil Cartier and use his clear SLC covering which is iron on and has a fairly good lifespan on foam. Eventually it does like to lift but most coverings do the same that are iron on but I've found Phil's covering to offer strength due to it's tensile strength.

         Application is done with a throw away sponge brush. Lessons I learned the hard way, don't wash out material to reuse brush with soap. Soaps are generally concentrated and soap reduces the surface tension of water therefore your paint goes on beautifully only to essentially run off of the model a few minutes later. Use one brush for clear and one for colors. Use de ionized water if possible but distilled water is better than tap water. Tap water is electrically charged as it's running through the tap and this can also prove to be a problem like above. Do flats and later roll the verticals of the model flat to cover. If paint is used on the verticals, it will run down and this stuff doesn't sand as it becomes quite hard. You need to create a natural break which is something I do at the mid point of the fuse top and bottom doing one side at a time.