I think I know the answer, but I am going to ask anyway!

[hudson hornet !]

Dupont 5717S, and 5718S-
What are they? Relabled ospho?

Should I use this stuff under SPI Epoxy? My gut says no but I want to ask and make sure. Are these metal conditioners needed today?

Thanks!

 

[chevman]

I would only them for rust removal, not converting rust.

SPI ONLY recommends three kinds

PPG, DUPONT, or the Ospho because we know what we are dealing with and all three have been out for many years and not changed with every batch made.

 

[Barry]

Just follow their instructions to a tee as they overkill the neutralization of the acid just like we recommend.
We have a lot of high end shops that do use these products and have for years under our epoxy.

 

[MX442]

Rule #1 and #3 from every painter must read:
*Never use a rust converter of any kind. NO MATTER WHAT IT IS.
*Never use a metal prep UNLESS you are fully aware of how to neutralize properly

Kind of confused. Where does Ospho fit it? Trying to decide if I should use Ospho or not.

 

[chevman]

I don't think you will find anyone that has been an active member on this site for awhile, who uses a rust converter.
​For rule #3 you have to consider the definition of metal prep, because it changes, depending on who is using the term. The makers of Por 15 think that the metal is prepped when the rust is covered with their product, but most of the people here think the metal is prepped when it is rust free and clean. So when Barry talks about a metal prep, he is talking about something that will get rid of the rust---Ospho.

Use it as a rust remover, not as a rust converter. If you can't get it blasted to absolute white metal, then use Ospho to clean out the pits, but you may have to keep it wet for awhile to get the job done, depending on how bad the rust is. It works by dissolving the rust, so scratching some of the rust off while its wet speeds up the process, just don't try to grind the rust out of the pits. A pick or a knotted wire brush on a drill works good.

 

[Barry]

Ospho is a metal treatment, rust converters are colored product that convert the rust to a primer.

 

[anotheridiot]

Its tough to determine with Ospho. Each place I go to find it writes it up differently. Put it on the rust, it dries where oxygen and moisture will usually sit and prepares the part for priming.

 

[MX442]

Ospho is a metal treatment, rust converters are colored product that convert the rust to a primer.

Thanks, Barry.
I'm going to give Ospho a try inside a door where it will not be seen again. For exterior rust, it gets blasted or replaced with new metal.

 

[anotheridiot]

See, my biggest problem, probably alot of peoples problems is that rust that is coming out between the rocker panel and the quarter panel. you can grind it, blast it, wire brush the gap till you heat the metal to being pliable, but you are never gonna stop it from rusting again.

I literally think you have to cut the weld to get between the pinch weld to fix these areas, but I highly doubt anyone does. This is where I want to find a product that will stop it.

 

[chevman]

If you think that is going to be a problem, several guys on here have shown that they cut out the pinch weld and weld a patch in to make it solid from one panel to another. Rusty428cj comes to mind.

 

[MX442]

See, my biggest problem, probably alot of peoples problems is that rust that is coming out between the rocker panel and the quarter panel. you can grind it, blast it, wire brush the gap till you heat the metal to being pliable, but you are never gonna stop it from rusting again.

I literally think you have to cut the weld to get between the pinch weld to fix these areas, but I highly doubt anyone does. This is where I want to find a product that will stop it.

I agree. Unfortunately it is not practical to dis-assemble the entire body to get rid of surface rust in each pinch weld. I'm going to flush with SPI W&G 700 and flood with epoxy. Then maybe cavity wax. As for the inside of the door, I cut out the bottom for repair. That will give access to use Ospho and rinse. Will follow up with epoxy, then weld the door shut.