Rust removal chemicals

[JimmyZ]

I just looked at the .pdf for DX products and didn't see the remarks RE sandblasted metal. Not to say it's not their advice. DPLF epoxy primer's pdf says that unless film build is thick you need to use wash primer(DX1791) or metal conditioner underneath.

It's true that the metal has a "tooth" after sandblasting. It will hold water much better than slick steel. If you try and drag a cloth, clean wipe or paper towel over it fibers will be left on the metal's peaks. Using a male-male plug on the end of an air hose behind your wipe down will remove most of the fibers and the fine layer of moisture clinging to the metal. (clean/filtered air) A light wipe with a tack cloth can get the rest of the fibers. An immediate bake in the sun completely eradicates any hint of moisture. This is restoration not production. A production shop doesn't care or have time to waste with such things.

You don't want to over rinse and wash away to much of DX520's deposits. If your dried treated metal looks a bit on the reddish side then you need to reapply and dry quicker. (Gold color is good) Working in a small area such as the roof or a panel at a time is a good idea.

Unless it's a pro doing the blasting I wouldn't reccomend sandblasting as an overall means of paint removal on our Z's. (thin metal) This is especially true with a pressure pot setup. You will have wavy panels. (Ask me how I know these things ) Sometimes the waviness isn't perceptible except by a bodyman or car freak. This is my opinion from the few vehicles I've done. I'm a believer in a good chemical strip followed by spot sandblasting.

2c

Jim

[five&dime]

Yeah..... The wash primer is what I use on bare metal. The guy that has taught me a lot about painting has said you CAN use epoxy primer on bare metal but it may not last as long as if you use wash (etching primer) first. It will gaurantee you a good bond with all your follow up layers.

I would say your fine either way. I just figure it's worth the insignificant increase in cost of materials to insure a good bond and a long lasting finish

[Seppi72]

One thing I think needs to be stated is that there is a difference (to me at least) between what people call "bare metal" and sandblasted metal. To me, bare metal is that piece you welded in to replace the rotted panel. It has a "mill finish" that, when compared to a blasted surface, is downright smooth. Perhaps, too, bare metal might be the designation that could be applied to the metal surface after you've sanded off all the previous coatings.

Regardless of that last sentence, bare metal is tremendously more smooth than blasted metal. Consequently, when someone says "do such and such on bare metal" I have to make the logical assumption that they ARE NOT talking about the metal surface that results from blasting. To me, they are competely different animals.

Obviously, we have at least several forum users who are highly knowledgeable on this matter and I'm claiming to be one of them. Do any of you mavens subscribe to the definitions I have stated above? Is there a spectrum of bare metal types?

I suppose that because I'm going to be contributing to their profit margins, I think I can reasonably ask both PPG and DuPont for their definitions of bare metal and expect answers:).

[26th-Z]

I have read that OSPHO is an encapsulator. It has a very low percentage of phosporic acid. I use it all the time for cleaning and metal prep. You are supposed to be able to paint right over it, but I wipe it off. The PPG metal ready is very good and I used it on my car before I primed it. I didn't sand blast my car and I don't agree with sand blasting but wiping it down with metal prep before you apply the primer is a good idea. You can use etching or non-etching primer at this point. It doesn't matter. I used etching primer inside the unibody because I couldn't wipe the metal and I used regular primer on the outside shell afterwiping it down a couple of times. Enrique should be in the conversation. He's the pro.

I see no difference between blasted metal and mill finish metal. There is nothing on the metal - it is bare.