Slime

[RPM]

IF anyone is brewing their own bio I could use some help. I was getting my feedstock from a place that kept it pretty clean. The place has gone out of business and now I am getting it from a place that cooks wings and other stuff. It still looks pretty good but it titrates fairly high. My issue is this, After it cools from processing it has a yellowish film on the top almost like a slime. I can pull it off most times and throw it out but if it falls apart it will sink. It happens nearly every time I heat it up. It will also have sort of a white/yellow slime in the bubbles if I agitate it (Run it through the dryer or circulate it). I am using 12 gallons of meth and five pounds of lye for a 50 gal batch. Is this soap or is this a residual fat? Seems to wash and run OK after is is all said and done but I have not had this happen before with the other feedstock

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2002 Laramie SLT quad cab long bed, 4X4, NV5600, Quad XZT+, 4" exhaust, BHAF, Outerwear & heat shield. Raptor 100 w/big line kit, Pyro, Boost and Fuel Pressure gages, 275 HP RV Injectors, Short shift kit, Bilstein shocks and 2" leveling blocks.