On Aug 21 I wrote about GooGone and Autoglym.....
https://www.hairlosstalk.com/intera...se-on-your-poly-surround.116550/#post-1704851
When you say you soak the hairpiece for 3-5 hours, do you mean that you pour the Autoglym into a bowl and soak the piece, or, do you spread Autoglym on the hp and allow it to sit (hopefully in a plastic bag) for 3 to 5 hours? As per my post on Aug 21, I spray GooGone or Autoglym on the lace side of the hairpiece. Place the piece in a plastic bag. Allow it to sit for at least an hour, preferable 1 1/2 or 2 hours. 95%+ of any adhesive residue is gone. Any remaining residue is easily removed using the magazine slide (glossy stock only), or the mirror/glass slide if you prefer. If you are following this procedure it is unimaginable to me that you still have residue after 3-5 hours.
As for your question about any harmful affects.....doubtful. Autoglym/GooGone have been used extensively for years. It is important to thoroughly clean the hp thus removing all traces of the solvent after this process. I soak the hp in a solution of hot tap water and liberal amount of shampoo for an hour. All traces of the solvent is removed. A thorough rinse/condition and I am done.
As an aside....I rinse from both sides...lace side and hair side. Mostly on the hair side. I have yet in 11 years noticed any hair pushed through the lace caused by rinsing on the hair side.