Carboy cleaning

[Spartus_12]

I saw a old thread how to clean carboy glass. I have some built up residue on the inside of the car boy that I'm having a hard time stripping off I'm stripping off. I am not sure if it is some sort of an oil based resin but I'm looking for the best way to strip it clean and bring it back to a food safe produit looks like these carboys came from some sort of a facility where they cleaned firearms and ammunitions so it can possibly be some petroleum based product. Any advice on the best product that I can use To start making it food safe ?
I have already tried D natured alcohol all the way up to acetone and zylene. If I have to switch to an acid are there?
Thank you

 

[3DDave]

Seems like a big risk and a lot of effort to save a few dollars. I'm a bit concerned that you misspelled chemical names, so maybe get out a credit card and buy new ones and take the ones you have and sell them to a firearms cleaning operation.