Help with paint prep, Need help with Ospho use |
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Help with paint prep, Need help with Ospho use |
sixaddict |
Oct 5 2021, 08:45 PM
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#1
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Senior Member Group: Members Posts: 839 Joined: 22-January 09 From: Panama City Beach, FL Member No.: 9,961 Region Association: South East States |
Have a glass blasted car in for paint. Needed to apply Ospho for surface light rust that developed. We are trying to determine how to neutralize before epoxy primer goes on.
Instructions say brush off dry powder then wipe with mineral spirits. In another section it says to etch wet with Ospho for 30 minutes then wash down with water. That seems risky due to flash rust. Anyone have experience to recommend which way to go. TIA Terry |
bbrock |
Oct 6 2021, 07:37 AM
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#2
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
That link about SPI is a good one and covers some things I didn't, like reactivating dry Ospho coat by rewetting with itself before neutralizing.
I'm not sure what Ospho was designed for, but it is labeled for etching bare metal for primer prep by following a different procedure that includes neutralizing. Also, PPG doesn't seem to mention any other products other than their own by name, but the directions for their DPLF epoxy primer include this: "Chemical treatment or the use of a conversion coating will enhance the adhesion and performance properties of the finished system." Lastly, I think Ospho (and other phosporic acid treatments) is different from mild acids like vinegar in that it forms a dry phosphorous coating after wetting with water which reduces the tendency to flash. It was a non-issue in my Montana climate but I notice OP is in Florida so YMMV. |
Superhawk996 |
Oct 6 2021, 07:45 AM
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#3
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914 Guru Group: Members Posts: 6,469 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
It was a non-issue in my Montana climate but I notice OP is in Florida so YMMV. Being in the midwest with 80-90% RH in summers, I fight flash rust on everything from sheetmetal to my machine tools. (IMG:style_emoticons/default/headbang.gif) Dehumidifier in garage has really helped. My garage isn't tightly sealed by any stretch. Can usually keep it down to 60% RH which really reduces flash rust potential. |
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