The Stovebolt Site Forums The Shop Area Paint and Body Shop Sandblasting off 6 layers of paint.

When its all said and done I was told to use muriatic acid which stops all rust, then prime. Is this true ? Thanx

It may be true for Lacquer but who uses that anymore? It absorbs moisture and we know what that means...
It is NOT a good idea if your using epoxy primer unless you really like doing things twice. (Now and when the job fails)
Get it stripped, use a good wax and grease cleaner and get some epoxy on it and your ready for the next step be that next week or next year.

IMHO, do NOT use Muriatic acid EVER. Sandblast it, and apply epoxy primer just as CASO said. If you insist on acid prep, diluted phosphoric acid maybe, but still not for me.

This is on your bus, right? With 6 layers of paint, how much rust can there be? Judging from your pictures it looks to be nice and solid, what has changed in the composition of that metal over the past 45 or so years that it won't hold paint anymore? Sorry, but I just don't buy into all the rust conversion/acid treatments. What primers are you planning on? Some of the epoxies out there have incompatibility issues with these acids, and not observing these issues may cause paint failure down the road. A properly media blasted surface is an ideal adhesion prep for epoxy primers without the need for rust conversion coatings.

Lastly, if you are media blasting the body, large panels like found on your bus can be left a mess by someone who doesn't know what they are doing. Here is some reading on the subject, pay attention to Porchdog's replies, he does this stuff for a living...without inflicting damage.


http://www.trifive.com/forums/showthread.php?t=72038

http://www.trifive.com/forums/showthread.php?t=47896


He warns against using sand, as it is caustic and in many cases contains salt crystals in the mix....so once it gets to the bare surface the salt starts the rust process. If this doesn't get cleaned off, it will cause problems under your paint.. He also doesn't use soda, as it presents adhesion issues just like the rust conversion acids. I'm certainly not here to tell you what to do or not to do, it's your vehicle. What I would suggest, however, is researching how each of your prospective steps will interact with the next, and what problems if any, that their use will present. Knowing all the info up front, you can make informed decisions on methods/products that are compatible throughout the process from start to finish.

Based on info from the forum I treated my bare metal with phosphoric, not muriatic, acid and then epoxy primed. The epoxy is still in great shape 3 years later. I did this because I used various hand held stripping devices. I could not get all the rust out of tiny pits and the phosphoric acid converts this to iron phosphate.

The sandblasting should have removed all rust where it could reach. I wouldn't use the extra acid treating if I had my parts sandblasted.

Chuck

I was going to use soda or sand blasting. There is glass beads as well ? The guy said it may warp out the panels. I basically wanna do this absolutely right the first time. There is only two small holes on this bus which will be cut out. So epoxy primer on galvanized steel is the way to go ?

the least troublesome for a large project like a bus is paint stripper, cleaned off well and then phosphoric acid wiped and epoxy primed ..... galvanized needs it's own treatment before paint works on it, vinegar helps - but why would you use galvanized??

Bill

I HOPE I DIDNT MESS UP, I HAVE USED MURIATC ACID TO REMOVE THE COATING OFF OF SOME NEW BOLTS SO I COULD PRIME ,PAINT THEM, RINSED ,SOAKED IN LAQUE THINNER , DRIED, PAINTED, WILL I HAVE APROBLEM DOWN THE ROAD? THANK YOU FOR YOUR ADVICE, BABE

I just sandblast, clean with a wax and silicone cleaner and spray with epoxy.

Simple, strong, lasts.

Then, scuff and top coat.

Done.