Tried a new rust converter on a '97 F-150 frame and it turned to goo

Had a customer's truck in the shop with some bad scale on the rear frame rails. Used this new gel-type converter that promised to turn rust black and hard in an hour. After two hours, it was still a sticky, brown mess that gummed up my wire wheel. Cost me an extra forty five minutes of cleanup. Learned that some of these new formulas are junk compared to the old phosphoric acid stuff I trust. What's your go-to for a solid frame prep before welding on a patch?

3 comments

3 Comments

uma3061mo ago

Ospho is the only stuff that actually works for me.

olivia4781mo ago

Wait, you actually use that stuff?

jason_robinson1mo ago

My old truck bed had rust spots I tried to cover for years. I used that rust converter gel from the hardware store and it always bubbled up again. After seeing @olivia478's question, I gave Ospho a shot on a really bad spot last fall. That area is still solid black under the paint, no orange coming back at all. It totally changed my mind on what actually works.