Primer after blasting, right away???

[Goosesdad]

Heading to the media blaster next week for a complete body blast. How important is it that I get it in primer right away? I live in Boise Idaho, pretty hot and dry right now but I also understand that any moisture in the air will start the rusting process. I would prefer to get started with the 4 link, cage and some of the body work without grinding through primer in order to weld....but.....not if that sacrifices the end result. Thanks in advance for any advice.

[rjsjea]

Prime it......running 80 grit over primer with a DA takes a few minutes to prep it for fab. Especially if your project's timeline gets pushed out as most do.

[dhutton]

Use a good quality epoxy primer and at least two coats to prevent rust. Blasted metal seems to rust quickly. I like to use Southern Polyurethanes epoxy due to the reasonable price, good quality and free same day shipping.

Don

[Goosesdad]

Thanks!!! Seemed like a rhetorical question but was hoping for some magic... Ha. Have a great day.

[Munssey]

I would agree to get it in primer as soon as possible. Just as a note..i've left metal bare for some time without flash rust as long as you keep skin oils and moisture away from it. I mention that for anyone who may have a delay in timing between the blaster and whoever is going to lay down the epoxy. Keep in mind, I'm in the dry\ warm Southern California conditions.

[WallaceMFG]

I just put cheap primer on mine to keep it from rusting, I'll sand it all off when its time for body work and cover it with good epoxy primer

[mitch_04]

I had a blasted pickup box in the shop for nearly a year as I installed patch panels on it. When it was ready from primer, the only rust was where my arms or hands rested on it during hot summer days. Hit it with some 80 grit and primed it.

That being said, if I were to do it again I'd prime it immediately. No worries if it needs to be set outside then, and the amount of paint you "waste" by grinding or replacing panels is very minimal, especially compared to the cost of blasting.

[renegade6]

Did the same thing here. The SPI epoxy is very easy to work with and a great price.

[mitch_04]

I am a big fan of SPI as well, great stuff for the price and the customer service can't be beat...ever!

[Goosesdad]

Thanks again. I will prime it ASAP after blasting. The threads here bring up a question. My painter buddy.....think he is good but ???...advised me not to put down epoxy first but suggested PPG NCR271. I went with his suggestion on the hood, fenders and doors. When I paid for it, I naturally assumed there were gold or platinum flakes in it but doesn't appear to be so. Thoughts ? I could make a change when I do the body.

[dhutton]

Thanks again. I will prime it ASAP after blasting. The threads here bring up a question. My painter buddy.....think he is good but ???...advised me not to put down epoxy first but suggested PPG NCR271. I went with his suggestion on the hood, fenders and doors. When I paid for it, I naturally assumed there were gold or platinum flakes in it but doesn't appear to be so. Thoughts ? I could make a change when I do the body.

That looks like a good primer but I don't see much advantage over SPI epoxy which is an etch primer. Many folks are using epoxy as their first coat on bare metal with good success.

Don

[Goosesdad]

Thanks Don

[Hogshooter]

Everything I read says you should chemicaly etch or spray etch prime bare steel before you put this primer on top. We used this same primer 20 years ago in the collision shop, I always sprayed etch on the bare metal, if it was a large area I epoxied the panel then put the building primer on it. Here is info from PPG.com.


NCP270/271
Directions for Use
Surface Preparation:












NCP270/271 Corrosion Resistant Primers
· Wash the area to be painted with soap and water, then clean with
appropriate PPG Cleaner.
· Sand the bare metal areas completely with 80 – 180 grit abrasive. Sand old finishes
with 320 – 400 grit dry by hand or machine or 600 grit wet. Exposed bare metal
should be spot primed with a suitable bare metal primer.
· Re-clean with the appropriate PPG cleaner.
· Two step metal treatments or the use of a wash primer coating will improve the
adhesion and performance properties of the finished system.
· A two step metal treatment or wash primer is required over sanded clean
galvanized steel substrate.
· Prime aluminum within 8 hours. Prime carbon steel immediately after cleaning.

[Goosesdad]

Thanks.

[mitch_04]

If you are going to do an acid etch, make sure to rinse while the acid is still wet or you'll have to start again. I've read of many down-the-road failures from letting the acid dry. Check out SPIuserforums.com for a bunch of good painting info, it's where I go to learn about the auto body side of rebuilding cars.

[Hogshooter]

The acid etch is old school if you are using a particular primer read that information and use the product exactly like the manufacturer states. We use the phosphate wash on steel like a new built trailer. On cars we use DPLF with DP401 catalyst for the etch and for corrosion protection.

[mitch_04]

Isn't phosphate acidic? Phosphoric acid?

[indyjps]

If you wipe it down well with metal prep degreaser, same manufacturer as your primer, it will get you some protection but I wouldnt go more than a few days. I recently had a car blasted, plan on a full day of blowing the car out in every direction, shop vac etc. Plan on DA'ING the entire car with 80 grit for a smooth consistent finish, your primer will lay down much nicer. No matter who the blaster is, you'll have rough patches that you'll want to DA. Some areas of my car were rough enough to pull fuzz out of the cloth used to wipe with metal prep. Don't shortcut it, everything else builds from here