• BASE COAT
1) Paint type -- The base coat can be anything really. Acrylic, enamel or lacquer--matt or gloss--but each does have its own unique properties. The brand of paint shouldn't matter because I've had similar results with base coats of Tamiya (thinned any way you like--lacquer thinner, Windex, etc.), Vallejo and Lifecolor. What is important is the quality of the finish. Any type of grain or orange peel will affect the end results. The smoother the surface for the white wash to adhere to the larger and more dramatic the paint chips will be. However, it is also more difficult to achieve smaller chips if the surface is too smooth (ie. you'll get a preponderance of large flaky chips on a very smooth surface, which can rapidly get out of hand--this was Marcus' problem I believe). I personally find some tooth from a matt paint surface gives a more realistic result (as it applies to heavily used combat vehicles) and this is what has worked best for me.
2) Primer -- But regardless of any of this, one thing I do almost religiously is add a primer coat before I do anything. Like a condom, this is the most appropriate form of protecting the plastic and the base coat will adhere to a primer coat better than bare plastic no matter what the circumstances or brand of paint. In the 50+ or so paint jobs I've done in the past few years, I have never had a problem with paint lifting from the plastic when I primer, so I don't waver in that area. To prove my point here even more, my recent 1/72 Pzr IV F1 only has a pre-shade of Tamiya NATO Black and sure enough, I cut thru to plastic on some of the edges of the hull. Mr. Surfacer 1200 aerosol is my best friend.
• HAIR SPRAY
1) Type -- If you read everyone's comments from around the world on the type or brand of hair spray being used, there is a broad variety. This has led me to believe that it really doesn't matter on the brand of hair spray. I have used the same can (still on my first) for all of my paint jobs and I really like it for both its ease of use, pleasant smell and fine misting qualities--Tresemme Professional series Ultra Fine Mist, which I bought in the US at Target. This stuff is so good my girlfriend now uses it herself (for what's its intended to do), I had to have her buy her own can because she kept coming and stealing mine. 😳 But see, that is the genius part of using hair spray, Because it was designed for use on humans it won't harm the model in any way and completely washes off with water. I have yet to see any adverse reaction to any base coat and only the salt technique is as user friendly in this regards, so trying to make this stuff work for you is worth the trouble in my opinion.
2) Quantity -- Here is an aspect that varies greatly between individuals. How much hair spray you apply does make a big difference in the speed in which the water reacts, the size of the chips obtained, and the ease of removal of the white or other top layer. (My feelings Adam, are that you did not apply enough or your hair spray layer was too thin and the results were that it took a long time to get the white off causing you to scrub more and more and eventually you cut thru the base coat. Frustration probably also set in making you scrub harder. My first diagnosis for you would be to add more hair spray). I apply two complete layers from about 10-12" away, letting each dry in between by using a hair dryer on low heat to speed it up. Note the glossy sheen above. However, if you know this about the technique then you can use it to your advantage. You see being able to control the size of each mark is where the power of the hair spray springs to the top, better than the salt technique even. Those of you obsessed about such things, like myself, will know what I am talking about. Hair spray allows you to get the smallest mark possible depending on what tool you are removing the paint with. So what that means is depending on the quantity of hair spray applied, you can achieve different results to your liking. My motto is "you can never have too small of a chip".
• WHITE WASH or TOP LAYER COLOR
1) Paint type -- OK, here I feel it should be an acrylic, but I do believe you can have similar results with enamels if you practice first. Again brand doesn't seem to really matter. For Tamiya users though, I will state that for the white wash step, do not thin Tamiya with Lacquer thinner this time because it will bite thru to the base coat to much. Stick with just water, it makes it easier to remove. I experienced both with my Pzr IV F1, the first layer of white wash was with Tamiya thinned with Lacquer thinner and it was hard to get it going. The second layer I just used water to thin the Tamiya white and found it much easier to remove.
2) Opacity -- Another very crucial area of consideration, maybe the most important aspect of how this process works. The entire point of using hair spray is so that you can remove whatever is resting on top of it by dissolving the hair spray layer with water, thus giving you these glorious chips and scratches. Again, nothing can be more simple or user friendly in theory. But unfortunately, that is just not the case. The opacity of the top coat is vital to success, and even more importantly, knowing how thick to apply the paint and what looks you are trying to achieve will make a big difference in the end result. It all relates, and I feel many guys who struggle here are probably spraying blind if you will, (especially beginners), and not realizing this factor plays a part. Obviously, the more opaque a top layer is, the harder it is for the water to get down to the hair spray layer. Remember you are trying to dissolve the hair spray, not the paint itself--the paint comes off when the hair spray comes off.
2a) Opacity/White Wash -- The best method for applying a white wash finish is to leave a fair amount of the base coat visible or visibly bleeding thru. The reason is that you want the water to get thru the white as fast as possible to affect the hair spray and make paint removal random and effective in a natural looking way. Here you are going for more extremes and have less concern for what remains. Done right the laws of the process take over and you have a rather random and natural looking result. So use less white in areas you want more base coat showing.
2b) Opacity/Non-white wash -- When using the hair spray for general chipping and going for effects that require removing the top layers in a random and controllable fashion, the hair spray is also a perfect tool to use. However, in this case you want even and uniform paint coverage because the top layers of colors are exactly that and not intended to be a deteriorating temporary finish like a white wash is. So how do we cut thru the paint to get to he hair spray? Here I use differnt tools like toothpicks, small awls, needles, hobby knife, anything that can easily cut thru once the paint softens a little from the water. When you apply the water, the paint will not dissolve but it does get softer, so this is how you very gently begin the process. There is a lot less scrubbing with brushes involved and more with making nicks and scratches with sharper tools. But again by varying the opacity slightly, like on the drive sprocket below, you can achieve the required amount of removal you are after.
• REMOVAL
1) Water -- The water is just that. I haven't determined any tangible difference between warm and room temperature water. Warm water probably works faster but I haven't seen any real variances of note. My only comment here is on how to apply it. I take a 1/4" wide flat brush and paint the surface with water once, nothing too much just get the model wet. This kind of softens the entire top layer in preparation for the scrubbing. While that is drying, I then pick a small area to work on like a front fender and then apply another layer of water and let it sit for 20-30 seconds. Then I begin to scrub and scratch, whatever I want the results to be.
2) Brushes & Tools -- What type of brush you is important, but like those illustrated above anything relatively short and stiff would work fine. Once the hair spray is wet you can pretty much do what you like to it. As the water takes hold and dissolves the hair spray, you will see the removal begin to happen as you scrub, sometimes very quickly, so don't be too aggressive. I take my time and when I begin to see the first marks appear I move in close and really concentrate so I can get the best results. I try to control the quantity of the marks as much as possible, so it doesn't get too out of hand. I also use other small instuments to create small nicks and scratches. Again anything relatively sharp will work fine, just use caution and don't stab the model. Move quickly and randomly to achieve the best results. The more you work an area, usually the worse it gets, especially if the chips are getting too large, so don't linger in one area too long.
Well, that is about as much as I know on the subject. I might be forgetting something, so please ask if something doesn't make sense.
Best,
Mike
