What are you etching--metal, glass?
I don't think Image Transfer Solution (ITS) would be my product of choice for etching; the ITS process involves coating the entire surface of the item you are applying the image to--it does not go on like a stenciled pattern which is what you need for most etching projects.
For etching metal, I just use a Sharpie pen to draw designs, or StazOn ink pad to apply a rubber-stamp pattern. The ink will protect the area of the metal from the chemical etching solution and leave those parts raised. The book "Semiprecious Salvage has good instructions on this process.
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