Painting via vinyl paint mask

[flavinny]

 I am in the process of repainting a 3.5-gauge model of the 1403 Western Maryland 4-8-4 and looking for help from anyone that has used vinyl paint mask for lettering etc.
 I intended to somehow get paint from shaker cans that I could mix to match colors then airbrush over the mask. A friend suggested using acrylic paints available from hobby shops. I don't know if that would be waterproof. (This is a live steam loco water and steam all over the place)
 " How to" would be appreciated and help in getting the correct color paint also.

[peteski]

I often "decant" pain from spray cans to spray it through my airbrush.  There is plenty of info on how to do this if you search the Internet for "decanting spray can paints", or something similar.  But some of the methods are not very safe.  I  never puncture the can!



I simply change the spray nozzle to one on which I installed a plastic tube.  I have collection of various such nozzles as different brands of paint use different nozzles.  Then I just spray the paint out thought the nozzle into an empty glass bottle.  Carefully, as the paint will bubble as it sprays out because the liquid propellant (usually propane) in the liquid paint expands to gas. Once you have enough paint, screw the lid back onto the bottle, but to not tighten it as the propellant will keep on evaporating from the paint for few days.  Also do not shake the bottle as the propellant can bubble up.

Once all the propellant escapes, the paint will be safe to use.  This sounds like a hassle, but it isn't really that bad. As I mentioned, I do this fairly frequently.

[TrainCat2]

Been there done A LOT of that. I use vinyl paint masks all the time. They work great but have their limitation based on the paint chemistry you will be spraying. Don’t use hobby store paints. I am a scratchbuilder of of giant scale RC planes. We use Behr outdoor water based latex primer + paint all the time. It’s water proof on your house so why not on other items. The real trick is mixing the paint to a consistency of coffee creamer and spray very light coats. Not uncommon to spray +8 coats and use can use a heat gun or hair dryer to accelerate the drying process.

The mask composition must be selected for certain paints. With Latex, you can use anything. For solvent paints, using any mask material not specified for solvents will cause bleed runs due to the solvent eating the glue out at the edges. Oramask from Oracal is great for general purpose stuff but you have to select the tackiness correctly. Fresh painted undercoating will want a lighter tack while a fully cured undercoat can use anything. Stay away from Oramask 810, that all I’m gunna say bout that! For solvent paint, don’t cheap out and purchase the Avery Dennison SF 100.