Gunk and other degreasers using petroleum
Hi Wayne
Gunk and other degreasers containing or mixed with petroleum, must be carefully cleaned off after they have been use on painted surfaces, particularly paint containing flatteners such as military paints. The petroleum likes to hide in the porous surface of the paint or metal. Cast iron is a particular problem. That it leaves a oily residue may not be all bad though if you don't plan to paint right away.
As suggested following the instructions would be a good idea, but maybe hard to do as the most recent jug of the traditional Gunk I purchase doesn't make any reference to cleaning surfaces for painting, nor could I find it on their web site. (Alex, I think you are right the instructions were there at one time.)
I still use Gunk because it's still one of the most effective ways of dealing with grease and dirt mixed together, short of steam cleaning.
Temperature and heat of the rinse water are the keys to the process below about 70F cleaning is slow to non existent. Rinsing with cold water seems to have a very limited effect may get the lumps of grease off but will leave oily residue. I use a biodegradable degreaser after washing off the Gunk solution. The hotter the water you use the better. Then before painting use Prepsol or another painting prep product. Once you have done all this to a bare piece of steel it will rust in a matter of days.
Cheers and happy parts cleaning Phil
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