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Thinning and Binding Acrylics

Discussion in 'Tackle Making' started by hazmail, Mar 15, 2008.

  1. Every week we see posts “How do I thin ‘X brand water based acrylics”? I generally use a combination of Tamia, Liquitex and JoSonja w/based acrylic paints (in layers). I have about 10 colors and mix any ‘specials’ from these.
    Basically water based acrylics are colored pigments mixed with a binder. You can make your own paints if you like, just go down to the paint store, buy the pigment color you want, and mix it with PVA glue (white) and water, probably not the best paint but it will work. If you thinned this paint with excess water, you dilute the binder (PVA glue) in the base paint and it will not stick too well, in fact it usually ‘beads’ into tiny dots and will not form a solid color (see pictures). This is caused by capillary action (lack of), where the water/pigment, maintains its meniscus, instead of spreading across a surface giving a ‘full coat’. The same will happen, with whichever acrylic you use, if thinned, it does not matter how much you pay or how good the sales pitch is, acrylics are acrylics, the variables are the grade of pigment and binders (mediums) used, any surfactant, and how fine all this is ground, so if you can afford it, buy good quality paints, which usually have, good solid pigment/colors - you get what you pay for here – until you start paying for the advertising, where the quality probably has to go the other way to pay for the adds.
    What’s a surfactant?
    “A substance that, when dissolved in water, lowers the surface tension of the water and increases the solubility of organic compounds. Surfactants are used in inks/paints to increase the effects of capillary action; detergents are surfactants that help remove organic compounds from a substance by making them dissolve more readily in the water in which the substance is washed.”
    Windex has been mentioned as a thinner and brush cleaner here, many times before, don’t be scared to use it. Windex is a mix of Ethyl alcohol, or ethanol (Methylated Spirit, here and U.K), some ammonia, mostly water, a nice blue tint and a surfactant (probably detergent), which makes this brew stick to glass; I’m sure we could make our own and it would probably cost about 10c a bottle.
    Glass is super glossy and ‘Windex’ has a surfactant in it, so when you clean a window, the spray covers the whole window, it does not just bead on the glass like water spray would. So instead of thinning your paints with water try some ‘Windex’ and you will find the thinned paint will mist on without beading. If you don’t have Windex, try a drop of dish washing detergent (the purer the detergent the better) or liquid soap - If you are into firefighting, or know someone who is, get some firefighting foam (a pint would last for years), its made by “3M” and is pretty well pure detergent ,which makes foam/water ‘stick’ to vertical surfaces. We use it here (and there too) mixed in water (3%) for bush fires, it allows water to coat Gum Leaves or any oily/glossy shrubbery and really helps extinguish the fire. See the logic here, ‘surfactants’ and ‘binders’ (matte mediums) are the key.
    This is black paint diluted 10:1 with water, sprayed onto Lexan sheet: notice how the paint has beaded.
    This is black paint diluted 10:1 with Windex, sprayed onto Lexan sheet: (dots etc are marks in the sheet)
    When I want to paint fine detail or add just a hint of color, I sometimes thin colors to about 8 or 10:1, so there is barely any color pigment or binders left in the mix. This is a good way to lighten colors without losing the hue, which happens if you lighten with white etc, spray more coats, and get deeper color. For this I use Windex, and because the paint is so diluted, I add just a drop of acrylic matte medium (any good brand) to hold it all together when it dries, mediums are not cheap, but a small tub will last for ever. This Windex/medium mix is handy when screening, especially when using ‘Pearls’, where the color will stick to the lure and not lift off and pool, when you remove the screen.

    If you use ‘Tamiya’ clear colors (probably shellac based), which they say are water based, and can be cleaned up with water, but if you thin excessively with water the colors just fall to bits. Again try some Ethyl alcohol, or ethanol (Methylated Spirit, here and U.K), when I buy a new jar of ‘Tamiya’, I immediately fill the jar with alcohol and shake it up and usually find it is still too thick, this stuff has good color pigments and takes heaps of dilution, and the thinner it is the less it gums up your brush tip. As a bonus ethyl alcohol is very cheap and is an excellent stripper for cleaning your brush, whether w/b acrylic or ‘Tamiya Acrylic’ and also Ethyl alcohol readily mixes with water.Pete
  2. fugarwi7

    fugarwi7 Lumberjack

    Who knew? That is really interesting...for a science geek llike me who prefers to know why and how things work...thanks...I can make no additional comments at this time as my brain is still smoking from processing your information!! :p