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Author Topic: Masks  (Read 1044 times)

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Offline Deerslayer

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Masks
« on: January 21, 2012, 07:31:21 AM »
 I occasionally like to hack around with airbrushing, despite my almost non-existent artistic abilities. Specifically, I have done a couple of basic jobs on model airplanes, such as scallops and some lettering.

 One thing that has been a real problem is how to mask shapes.

 I have tried a couple of different varieties of liquid masking, with some success depending upon the material being masked. This still requires that I make some kind of pattern to assist with laying down the liquid mask, plus I often had to re-apply a second coating and/or make some corrections. You also have to wait for quite awhile to enable proper curing of the liquid mask.

 I tried using frisket paper. Apart form being expensive, it didn't work for me on curved surfaces without really pressing it into place; later, when removing it, the covering material wanted to pull away from the balsa.

 I also tried using some "Stretch 'n Seal" film. It works well, if you can cut the stuff neatly to begin with, but I found it too difficult to work with for anything but the simplest of masks.

Something like a Post-It, but cheaper and more flexible and available in large sheets, might be the ticket?

 One day, while covering an airplane with coloured Ultracote, I was about to throw out a big bunch of its backing material, when I had an idea. A rare occurrence, indeed, so I have the exact date and time recorded!

 This material (the white stuff, not the transparent film used to back a semi-transparent covering film) is a paper or plastic with some sort of shiny (wax?) coating on one side. Why not try making masks from it? No, it would not stretch, so it may not work for some areas involving compound curves, but I'm pretty much a 2-dimensional sort of guy, anyway!


So, here's the deal:

Take a piece of this backing and lay it out flat, shiny side down, using weights or masking tape to flatten it out, preferably on newspaper on the floor or bench. Then, very lightly mist the dull side with a spray-on contact cement, such as 3M77 or Elmers Spray Adhesive. Let it dry, at least 1/2 hour. The idea here is NOT to make a strong adhesive surface, but to make my pseudo-Post-It sheet.

After this has dried, I see if it wants to stick to a piece of window glass that I use to cut things on. If I am not completely satisfied, I may re-spray and wait awhile longer.

Now, lay this piece of masking material, sticky side down, on the glass working surface. Then, cut the required mask, using an Exacto #11. When done, the mask can be lifted off the plate. If it doesn't want to start to lift easily, stick a little tab of masking tape onto  an edge or corner to make a little tab.

Apply this mask to your target area, press it down securely but do not over-do it. Spray (or brush) your paint on. Particularly if you are brushing, go lightly so that you avoid any bleeding under the edges of the mask. I you are airbrushing, go lightly so that you don't force paint up under an edge, or cause runs. With the latter, use several very light passes (I find, but then, I am a rank amateur and therefore not into the subtleties of creating various textures!).

You should be able to almost immediately lift off your mask (if you airbrushed), or in a very few minutes (if you brushed). Be careful not to smudge your creation. You want it to look good for that first trip to the field; if it survives the day, you will worry less about minor imperfections as time goes by.

One of the nice things about this technique is that your masks are reusable. The can be easily stored, rolled up or flat with with some wax paper between them. If they lose their stickiness, just re-spray. They are tough, so you don't tend to rip them.

This is a cheap and effective way to learn and it makes good use of something that you would otherwise send to the landfill. (Another use for this backing material might be as a shelf liner in the kitchen, but don't mention that until you are sure that you will not regret giving away this valuable resource too hastily. I cam really close to making that mistake ...)


Addendum:

 There is a trick that Jim Thompson once told me about to avoid paint bleeding under the edges of a mask. I have not tried it, but it makes good sense. He applies the mask, then sprays (brushes?) some CLEAR paint in the area of the edge. Now, this tends to seal off the edge a bit, so that subsequent application of paint will not bleed under the mask. Any minor bleeding should be of the clear only. Sounds good - so why not try it!
« Last Edit: January 21, 2012, 07:44:43 AM by Deerslayer »
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