Excessive flash rust after ospho neutralization

K

Kajpaj

New Member
Howdy folks!

I’m a total newbie, so I apologize for uninformed questions. I recently got my 76 Datsun sandblasted and due to metal quality I opted to Ospho the surface prior to using ŚPI epoxy primer (in retrospect a bad decision after speaking with the technical support at SPI).

I followed the ospho neutralizing steps outlined in the TDS and I have a lot of flash rust, please see attached pictures.

The gentlemen at SPI (super nice and patient) mentioned that some surface rust is fine and to paint over it, however they did not see pictures hence me posting here and asking.

So… I’m humbly asking for what I should do next since my wife will dump my car in the ocean if I send it to the sandblaster again (she wouldn’t, she is very supportive).
Can I just prime over the surface of should I bust out the DA sander and get it down to bare metal?

Cheers and thank you for the advice!
 

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Thanks guys, car is in the garage that is heated to dry, I’ll post some more pictures tomorrow morning, I fear it will be worse..
 
Never got around to taking pictures, I spent some time this morning with a 80DA and wire wheel to clean things up, will post pictures tomorrow when I have better light.

The question that I have is even if I manage to get the surface to a sealable state, would it not be better to get the car reblasted at this point? It’s money down the drain since I just got the car blasted, but spending 5-10 hours getting it cleaned up for an inferior result is not appealing either.

Kaj
 
Kajpaj said:
Never got around to taking pictures, I spent some time this morning with a 80DA and wire wheel to clean things up, will post pictures tomorrow when I have better light.

The question that I have is even if I manage to get the surface to a sealable state, would it not be better to get the car reblasted at this point? It’s money down the drain since I just got the car blasted, but spending 5-10 hours getting it cleaned up for an inferior result is not appealing either.

Kaj
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No point in doing that, as it will get the exact same surface rust again before you can get the epoxy on, requiring 80 grit on a DA again. The epoxy over the 80 grit is ideal for adhesion.
 
RenewAP said:
No point in doing that, as it will get the exact same surface rust again before you can get the epoxy on, requiring 80 grit on a DA again. The epoxy over the 80 grit is ideal for adhesion.
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Good morning, the rurface rust came after the ospho neutralization. What I’m contemplating is blasting it and sealing it with no treatment between.
 
Kajpaj said:
Good morning, the rurface rust came after the ospho neutralization. What I’m contemplating is blasting it and sealing it with no treatment between.
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No don't blast again, because blasting stretches the metal if not done right. If you've neutralized the ospho and have gone over the flash rust with 80 grit then there's nothing to blast, you do not have an inferior substrate. What you're seeing is normal, it's done all the time with the exact combination of products you're using.
 
You mentioned a wire wheel. I thought they were not preferred due to adding a little polish to the metal rather than tooth for the epoxy to bite into.
 
John is that the panel that you showed in other posts being welded? IIRC you used a MIG? That looks amazing. Like a TIG weld really. For being pretty young (under 40 you'll understand soon enough:)) you have some impressive skills.
 
Thanks dudes! Chris, its same F100 door as the other posts. Mig welded with a ~25 year old Miller 130xp, .024 ER70S-6 wire, 3-4 weld dots at a time (spread out over the seam), dots planished before the next round of weld dots. Robert has posted the technique before.
 
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