sheetmetal prep for painting

SDE · Oct 13, 2018

This is a 9n fenders and hood project. They were completely rusted. I welded some spots on the hood and welded patches into the fenders. I sanded as much rust off of them as I could. I then coated them with Ospho. They are now black and white. What do I need to do to the panels before I use body filler on some of the dents? Or can I apply the filler over the Ospho? After I sand the filler, do I wash them, prime, and paint?
TY
SDE

Stephen Newell · Oct 13, 2018

Assuming you washed the Ospho off and neutralized it then the next step should be an epoxy primer. Rust is hard to kill and if you put anything else over the top it could rust under the paint but the epoxy primer will stop it. You can put a fiberglass filler over the epoxy primer and sand it as though it wasn't there. It's just when you think you have everything level put another coat of epoxy primer over the fiberglass filler. Usually there is spots you missed or didn't quite get it level so you could use a filler primer over the epoxy primer. Epoxy primer doesn't sand well and the filler primer would serve that process. If you have any doubts on your body work you can use different colors filler primer and alternate colors with each coat. When you do the between the coats sanding the high places will sand through telling you it's time to stop sanding. This procedure is called a guide coat.

jd man wis · Oct 15, 2018

Say I have an john deere a that I got at a sale that the guy was fixing it up and he replace the hood and fuel tank and both are new and looks like there made out of galvanized and what should I do to them before I prime them. There is nothing on them now there bare. Thanks Stephen

SDE · Oct 15, 2018

I was not sure how to neutralize the Ospho, so I googled it. I got yeses and no s on whether it needed to be done. Some said to use water and others said to use soap and water. So here is my plan. I am going to re wet them with Ospho, Wait two minutes, wipe them off, and then wash them with a TSP and water solution. I might be able to prime them this week. Weather forecast is for Thursday and Friday to get up to 50. Unfortunately, I will have a funeral to attend this week and I am sure it will kill one of those days.
TY
SDE

Stephen Newell · Oct 15, 2018

Painting galvanized is a different animal. If you wish to use epoxy primer it would be necessary to sandblast most of the galvanized coating off. Another option would be to wash the metal with white vinegar and rinse clean. Then use a primer like you would use on aluminum such as Dupont Variprime. That is probably the best option if it's new metal without rust rather than remove the galvanized coating.

sheetmetal prep for painting

SDE

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Stephen Newell

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jd man wis

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SDE

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Stephen Newell

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