Name: Syreeta

Message: Hello there.

I thought I would ask you before I try just in case it goes wrong. I know that "all-purpose" dyes have acid and direct dyes in them and it's the acid that does all the work. What my question is, is that I'll be using Dylon's Multi Purpose dye to try and dye a white plastic item (I'm based in the UK and unable to get hold of products like Krylon's special fusion paints). I read from an old link on one of Dylon's websites (Australian one I think) saying that you SHOULD NOT add salt if you're dyeing buttons (or any other item). 

I've been to a modelmakers forum and a guy there said he dyed some plastic tyres for his model cars black and ADDED SALT (as well as used a method without a stovetop and pan, which he says will prevent some plastic items warping). What I want to know is what would happen if I ignored Dylon's warning and added the salt and tried dyeing my item the way the guy on the forums did it? Would the salt actually improve the final result or make it worse? just to let you know, the item will be a computer mouse (just the casing of course), as I can't buy the colour I want and skins don't exist.

Please let me know your thoughts on this. Thanks in advance!

Adding salt is done when you dissolve the dye in a relatively large amount of water, so that the electronegativity of the dye molecules and the fiber molecules doesn't make them repel each other.  The salt will not help to fix the dye, but it helps dye to get where it needs to go. There is no reason for you to add salt to your dyebath; there is already salt in the Dylon Multi Purpose dye. I don't think it will make any significant difference if you add more salt, though, unless your dye is concentrated enough that the salt causes it to come out of solution. Salt reduces the solubility of dye. In some cases adding too much salt will make the dye color more mottled, less smooth in color.

What you might want to do is add some plain distilled white vinegar. Vinegar is an acid, and acid dyes work best in the presence of an acid. (The dyes themselves are not acids.) This will help only if you are dyeing nylon, however (or a protein-based textile fiber such as wool). It will not make any difference for most plastics other than nylon.

I hope that you can get another computer mouse to use if your first experiment does not work out. It really helps if you have an inexpensive source of parts. If you have a broken mouse on hand, you could try running tests on it before you dye your good mouse.

In general you will get darker, more intensely colored results if you heat your item in the dyebath to a simmer (87°C), but of course there is the risk that you will warp the plastic if you do. I can't predict whether you will get good results without heat, or even with heat, since I don't know exactly what plastic it is that you will be dyeing. Hot water will work better than cold water, but many plastics will not accept any dye at all. It looks like the plastic a computer mouse is made of is most likely ABS plastic (acrylonitrile butadiene styrene). You might be able to get some multi-purpose dye to soak into this material, depending on the color you want; we won't know until you try. I doubt that you will be able to get anything darker than a pastel color, at best.

I think that you will get better results if you use a product called vinyl dye. You can buy vinyl dye in the UK by mail-ordering it from a company called US Automotive. I don't know anything about this company, not having ordered from them myself, but the vinyl dye that they sell will probably give you the best results, if your mouse is made of a plastic other than nylon. Apply multiple thin coats if necessary to get the desired color; don't apply a thick coat. Vinyl dye is somewhere between a dye and a paint in the way that it soaks into the plastic only partially. Even better, I found a UK source for Krylon Fusion paint. This would probably be the best choice for recoloring your computer mouse.

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