I've found that it's thicker after sitting on the shelf for 5-10 years, but I doubt if that's what you meant by your question. It should become thicker if you can get some of the water vehicle to evaporate without having the glue set up, but that would be a very tricky matter of timing and heat.
Or, as the Wiki article states corn starch may be already available in your kitchen. I've never used it other than in cooking but it is a thickener especially with heat. Do experiment, however. Ben
