Originally Posted by deadbodyman
lizer,your zink phosphate sounds promising I'll pick some up and try it and compare it to Ospho but you have a few misconceptions about "ospho" ..Yes it's active ingrediant IS phosphric acid but it does not need to be neautralized just like an etching primers main ingrediant is Phosphric acid ,you dont neautralize that ...it does offer protection against surface rust....and although SPI does noy recomend using ANY treatments thier epoxy primer works very well with it ...I know first hand because I've been using ospho for for around 25 yrs and SPI has been my primer of choice for quite a few years also..At my shop,if I strip it or its blasted its gets the combo,
This is the first I've heard of the zinc so I'll try it on something and do a couple tests but the reason I still use ospho is because it works SO well and when something works well you stick with it...untill something comes along thats better...This zinc may be it ....we'll see
Is Ospho the same stuff as naval jelly or is there something more special about it? I have naval jelly I use too but this is in contrast to everything I've ever read about it, namely offering protection against surface rust. Even the label on my naval jelly states that I need to cover bare surfaces immediately or rusting will occur. Zinc is an ingredient alongside phosphoric acid in etching primers too
The phosphoric acid etches the surface of the metal on a molecular level, which forces the zinc into the metal. This is essentially what confers any hint of corrosive protection the primer may have.
I'm a research scientist by day and through my job have access to the thousands of scientific journals available. When I choose my metal preps I study the chemical interactions that take place, and the peer-reviewed scientific literature has a plethora on this. There's a good abstract on zinc here and it's a short paragraph:
I know it's a little nerdy than what most people might care for, but a scientist and an old body guy could be a slam dunk dangerous combination!
With all that being said, I don't want to talk zinc phosphate up like it's a miracle product, because it's not. I'm often hasty in applying it if I just want to keep the panel as bare metal for awhile, and flash rust WILL come back if I don't do it well. If I do a poor job sometimes the panel will flash before my eyes at the end when I'm wiping the excess off with a damp rag.
I originally learned about it from an oooold body guy who professionally restores Mustangs (the first time I ever met him, he rolled out from underneath a Mustang he was prepping at the ripe age of 77)