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**raggedjim** · 09-22-2017, 04:30 PM

I like OSPHO, I think it is phosphoric acid. I'm pretty sure the Metal prep that you put on before POR-15 is phosphoric acid, but I may be wrong.

Good luck, Rg

09-22-2017, 04:30 PM	#3
raggedjim Senior Member Join Date: Jun 2002 Location: Murray, Kentucky Posts: 3,386	Re: Heavy surface rust treatment I like OSPHO, I think it is phosphoric acid. I'm pretty sure the Metal prep that you put on before POR-15 is phosphoric acid, but I may be wrong. Good luck, Rg __________________ Roger '68 Short step - https://67-72chevytrucks.com/vboard/...d.php?t=849675 '69 ('70?) 2wd Blazer '70 GMC Jimmy 2wd