I wanted to make the sticky black slime using the ingredients I saw on YouTube. It consisted of Borax, Liquid Starch and Glue. I used 3 gallons of white glue, some black paint for color and just small portions of each of the Borax and Starch. The Borax almost immediately started to make the glue mixture clump into rubber like globs that weren't able to squish back out. I used more paint, water, shaving cream.... but nothing seemed to work. The more I worked mixing the worst it got. Not I have a 5 gallon bucket of rubber stuff. Not fun at all So if you're wanting to try this out, mix the powdered Borax with water first, that might work better... but not too much.
I have used borax and water solution mixed into a glue and water solution with good results. Most recipes I have seen call for borax or starch, not both, as they do the same thing chemically. Adding water and slowly stretching and stirring may be able to loosen it up.
For cleanup, vinegar will break the bonds made between the glue and borax, turning it back to original consistency.