Go down to Ace hardware or Home Depo and get the drain cleaner in the black plastic jug, pure lye, comes in its own plastic bag around it. Same thing in those other cleaners (Super Clean) but in lower concentrations. WEAR long gloves designed for this stuff, also glasses. Follow directions on jug. A friend worked in the meat department at A&P and when floor got to gummy from the cuttings he would get Draino and mop the floors. That stuff would eat up street shoes so he used his fishing boots, when done floor was spotless. Don’t get the ‘safe’ stuff, useless, has to say LYE. Also eats rust, paint, scum when put in vat. That's all furniture strippers use, WEAR protective gear!!