1973Guppie said:
bump....anyone else??
again, looking for info on the surface prep after sandblasting and what one should do and what primer to use, not a body shop guy here so sorry for the cluelessness. Basically looking for what steps I should take after blasting, is a spray over with compressed air (to get the glass beads off), wipe down with solvent and primer sufficient? what type of primer can I use that would come in a rattle can? I know I have seen "automotive primer" before, would this work? I basically just need to get it blasted, weld in patch panels and then all the bondo/bodwork will be outsourced, but I don't want to screw something up by putting on the wrong primer and have it cost me more $ because the bodyshop has to restrip the primer off. Any info on this appreciated. What are the steps others have taken after sandblasting?
Also, I just tested the Husky sandblaster I got from home depot, a cheapie $10 POS that comes with the gun and a hose that goes into a bucket of sand, industrial blasting sand bought from HD. I was surprised to see that even at 100psi this thing did little to remove paint. Do other sanblasters that come from harbor freight work better or ? If I wer to use this thing i would be blasting for a week straight to get the truck done. Any reccomendations on sanblasters others have used from HF that have worked well for you would be appreciated. Thanks for the bandwith on this issue.
Noah
A suction blaster, like the one you got from Home Depot, is not very powerful and very inefficient. Uses a lot of sand and air and works very slowly. You may be able to improve the performance of the one you bought by changing the nozzle size. TP tools makes a suction blaster with a highly refined design that works better than you might think it would but still not good at all compared to a pressure blaster.
A pressure blaster is a pressurized pot that mixes the sand and air inside a sealed container and sends the mixture through a very heavy-duty hose. Uses less air and sand and is more powerful. The HF version will work better than a suction blaster but a made in USA version like the ones sold by TP tools work very well. You need a huge air compressor to run one of these and even then you can't run it all the time. This uses about 1/2 the sand to do the same job and even though you need more air to run one, it's still uses less over the life of the whole job.
More powerful pressure blasters can be rented that run of a diesel trailer. These are amazing, they can be run as long as you need them and are too powerful to use to prep body panels. Last year, I used one to prep my frame for paint. I was able to blast the whole frame in about an hour using black beauty. I did use a ton of sand. It made a huge mess. Like I said, I am done with doing it DIY.
To make an analogy, using a suction blaster and a small 110V air compressor to clean off rust and paint would be like using a garden sprayer to clean mud off your truck. It will work but not well.
Using a portable pressure blaster like the kind made by TP/Eastwood is amazing; they will blast off paint and rust like fresh mud comes off with a garden hose.
Using a large diesel powered pressure blaster that runs off diesel powered trailer compressor would be like using a fire hose to clean mud off your truck. Way overkill for most except for thick steel like frames.
Suction blaster is probably best suited for small jobs and or for use inside a blast cabinet.
To answer your question about surface prep:
1. Wash it very well before you even start blasting. Hot water with a strong detergent - I use dawn dish soap or metal ready from POR. If you don't, whatever grease, oil, wax, etc, will get worked into the metal and could contaminate the primer/paint. Often this can cause fish eyes or other funky paint problems.
2. Once dry, sand blast.
3. Wash again, first with soap and then you mix water and a product called panel prep from your local auto body store - basically a weak acid that preps the metal, conditions it and takes care of the flash rust (with a mild acid).
Once you have sand blasted, the steel will start to rust right away. In a humid environment, it will flash rust in 45 minutes. You might not be able to see it, but if you took a rag and some lacquer thinner it would come off rusty when you wiped it down.
If you can't paint in 45 minutes, keep it out of the rain and wipe it down later with panel prep. Don't hose it down with WD40 if you want to paint it any time soon, even though WD40 was invented to keep rust off, it's hard to get it all off before you paint.
-Stumbaugh