Vinegar to prep metal?

[NorCalGal]

So here's a picture from under my front fender after soaking in vinegar. How clean does the metal need to be? I have some pits after cleaning that look a little dark so I tried soaking some more and it looks the same. I will be spraying spi epoxy.

[NorCalGal]

Also does vinegar need to be neutralized? or is it the neutralizer?

[ratfreak8871]

Interested to see some replies. I stripped my roof last year and the entire roof was black and nothing touched it.

[mongocanfly]

1 cup baking soda to 1 gallon of water....is what the net says...another says soap and water....another says oil....obviously you want to get it dry and put some epoxy on it as quick as possible

[NorCalGal]

Is the baking soda to neutralize the vinegar?

[MP&C]

If you are using SPI epoxy, give them a call on the Tech Line and get the proper neutralizing process from the horse's mouth.

[tinydb84]

You definitely want to neutralize it. SPI is slightly acidic if I remember correctly. Talk to Barry. He is very responsive.

[nikwho]

I would think that the vinegar would need to be neutralized. Being that you still have some rust down in those pits, I would personally use some phosphoric acid on the panel, to neutralize the rust. I have had good luck with it in the past, but i will tell you that I am not a professional painter, by any stretch! I have cleaned panels with soap and water, then with phosphoric acid, then with mineral spirits, then wax and grease remover, then, after tack cloth, shot with epoxy primer. I have had no adhesion issues do it this way.

Nik

[Foot Stomper]

Any treatment that involves acid or water as a followup is likely to contribute to rust or coatings failure.

I say this because I've never seen in a technical data sheet (I've read many in the coatings profession) where acid or water is recommended or mentioned.

What I have seen repeatedly is clean, bare steel coated with epoxy primer, then top coated. Absolutely no mention of acid or water...

[StingRay]

Actually PPG DP40LF used to recommend phosphoric acid prep followed by phosphoric acid with zinc. This was only 10 years ago. Metal prep used to be very common across many paint lines.

Originally Posted by Foot Stomper

Any treatment that involves acid or water as a followup is likely to contribute to rust or coatings failure.

I say this because I've never seen in a technical data sheet (I've read many in the coatings profession) where acid or water is recommended or mentioned.

What I have seen repeatedly is clean, bare steel coated with epoxy primer, then top coated. Absolutely no mention of acid or water...

[nikwho]

Originally Posted by Foot Stomper

Any treatment that involves acid or water as a followup is likely to contribute to rust or coatings failure.

I say this because I've never seen in a technical data sheet (I've read many in the coatings profession) where acid or water is recommended or mentioned.

What I have seen repeatedly is clean, bare steel coated with epoxy primer, then top coated. Absolutely no mention of acid or water...

I agree with you, I would prefer NOT to use phosphoric acid. But, he has pitted metal with rust in the low spots. I suppose that an arguably better method would be to media blast the panel to get to clean, bare metal, but then, depending on media used, and blaster knowledge/experience, you are possibly going to get into warping issues. Plus, if he sprays epoxy primer over rust, he'll likely run into much bigger adhesion issues than if he neutralized with acid, then cleaned it. The problem with the pitting is HOW to get to clean, bare steel, coated with epoxy, as you mentioned. How would you get there?

[NorCalGal]

Yes, I painted a 67 Camaro in the 90s that my autobody teacher recommended I use metal prep then a conversion coating under my dp40 epoxy. So I guess my real question is how does one clean rust off of metal and be assured it is clean. Sanding can not get into the pits, maybe I'm being too anal about it. Seems like this is a subject that never really has a clear answer.

[nikwho]

I don't think that it's too anal! You need to take care of that rust before you coat it, or it will show itself another day, which would suck! I like phosphobic acid, but I am NOT a professional body man! So, take my advice with a grain of salt! I'm sure that guys with far more experience than me will (and have already responded!) respond to this thread.
Nik

[suprachrgd82]

Originally Posted by nikwho

I would think that the vinegar would need to be neutralized. Being that you still have some rust down in those pits, I would personally use some phosphoric acid on the panel, to neutralize the rust. I have had good luck with it in the past, but i will tell you that I am not a professional painter, by any stretch! I have cleaned panels with soap and water, then with phosphoric acid, then with mineral spirits, then wax and grease remover, then, after tack cloth, shot with epoxy primer. I have had no adhesion issues do it this way.

Nik

Right on the money. Phosphoric acid stops the rusting process by converting the iron oxide to phosphorus oxide, visible results are the color change from brown to black. This method will yield flawless results.

[Foot Stomper]

This is worth a read if you don't already know what SSPC3 means.


http://www.inspection-for-industry.c...-cleaning.html


Epoxy requires a SSPC3. Nothing more for proven results.

[e015475]

I'm not a professional painter either, but my paint and body guy isn't happy with priming a panel unit it is all raw steel - no brown/black pits permitted. They either need to come out with sandblasting or I have to work it for what seems like hours with a DA with 80 grit, then multiple passes with a Scotchbrite pad and PPG metal conditioner until the surface is uniform.

I understand that vinegar is an acid that will remove rust, but it seems to me that you'd want to follow the paint manufacturers directions to a "T" and do exactly what they recommend. Using vinegar and then neutralizing it isn't a process they'd recognize and why build a shaky foundation to a project you're potentially going to add hundreds of hours of labor to?

Foot Stomper's explanation of the cleaning standard is good info, but it basically says "if you can't sandblast, here's how to clean the metal"

My suggestion would be to sandblast the pits and remove all traces of rust then follow up with the conditioner the paint manufacture recommends.

Just my two cents

[scott123]

It is one of those old school methods.

My uncle did body work in the 50's and 60's, back when they used lead as filler. Vinegar was a good way to clean the lead surfaces.

It is also a good method to prep galvanized for paint.

But like it has been posted, I'd go with the manufacturer's directions for what is going to be on top of the treated surface.

S

[NorCalGal]

Called SPI today for rust removal recommendation
1. Clean and degrease part.
2. Sand metal to remove most of the rust.
3. Paint thin coat of ospho on the part let soak 20 mins or let dry over night for heavier rust, you may have to reapply a second time.
4. You must reapply ospho to reactivate before rinsing with water
5. Then wash with lots of water and clean cloth.
He told me Ospho can be purchased at Home Depot or Lowes for about $30.00 but I can't find it anywhere here in CA. and it's twice that price on line.

Anyone in California have you been able to find or is this something else we can't buy here

[tinydb84]

Look for phosphoric prep and etch. They sell it at home depot.

[richards72chevy]

I would just wipe it down with lacquer thinner that stuff neutralizes any thing.I would be concerned about the rust pits though.

[nikwho]

Originally Posted by NorCalGal

Called SPI today for rust removal recommendation
1. Clean and degrease part.
2. Sand metal to remove most of the rust.
3. Paint thin coat of ospho on the part let soak 20 mins or let dry over night for heavier rust, you may have to reapply a second time.
4. You must reapply ospho to reactivate before rinsing with water
5. Then wash with lots of water and clean cloth.
He told me Ospho can be purchased at Home Depot or Lowes for about $30.00 but I can't find it anywhere here in CA. and it's twice that price on line.

Anyone in California have you been able to find or is this something else we can't buy here

Here is a link on Home Depot''s website for $16. This is also what I use.

https://www.homedepot.com/p/Klean-St...0220/100406369

I saw it on ebay for $36, which is more than double, but still cheap to get good results!
Here's that link:
https://www.ebay.com/p/Klean-Strip-G...e58357fffe61eb

[nikwho]

It's sold at Home Depot (and other hardware stores) as a concrete etch, to be used before applying epoxy floor coatings. So, another option would be to find a local epoxy flooring installer in your area. You could ask him if he etches with phosphoric acid, then ask him if you can buy a gallon from him.

[nikwho]

I have used the phosphoric acid in a spray bottle before, but it's not friendly to the lungs. I normally just pour some in a small cup and paint it on. Any time I go get some of this stuff from H.D. I always grab a big handfull of their $1 cheapo paint brushes from the painting department. That's how I did my '67 Pontiac. When I got it, the entire body was covered in superficial surface rust. I would paint on, leave for 10-15 minites, then wipe off and repeat. You CAN wipe it on, then leave it as in convert's the rust to an inert substance, but I don't like leaving it. The converted rust will eventually start running and dripping off of the metal. I repeat this until I'm down to shiny clean metal!

[BD70CST]

Originally Posted by NorCalGal

Called SPI today for rust removal recommendation
1. Clean and degrease part.
2. Sand metal to remove most of the rust.
3. Paint thin coat of ospho on the part let soak 20 mins or let dry over night for heavier rust, you may have to reapply a second time.
4. You must reapply ospho to reactivate before rinsing with water
5. Then wash with lots of water and clean cloth.
He told me Ospho can be purchased at Home Depot or Lowes for about $30.00 but I can't find it anywhere here in CA. and it's twice that price on line.

Anyone in California have you been able to find or is this something else we can't buy here

I know this is a few months out, but I found it at a Sherwin Williams in Roseville (I think it was Roseville). Call them and ask.