Thread: media blasting ?

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Getting prepare to clean up the under body and of my car. I don't known what media will do the best job, promote easier clean up and less hazardous, need help.
also read the complete thread that Bob posted and I will be wearing a respirator and saftey glasses.

If you want to get the undercoating off, sand is best. For any topside panels, a plastic media will remove paint pretty well. You can "spot treat" any topside rusty areas with sand.

You need more than glasses. Get a blasting hood !!! That damn sand will never come out of your ears.


WHAT???

HUH?????

I should have said I do have a hood, I plan on applying pro 15 to replace the under coating.

Sand is the most economical, not the safest, and probably one of the easiest on your equipment. If you actually have undercoating still sticking to the sheet metal, frame, or suspension parts, remove it my scraping and washing with gasoline. It takes sand forever to wear off undercoating, removing it prior to blasting will save you a tremendous amount of time, sand, and air, not to mention your sanity. Gasoline is dangerous, and it stinks, but it sure gets that black crap off in a hurry.

Be sure to use a blast hood alright, or you'll have so much sand in your eyes, ears, and nose that you'll be sick. Sandblasting takes one heckuva lot of air, so I hope you have a BIG compressor for the job. You don't necessarily need a respirator, although I'm sure it won't hurt to be extra cautious around any silica bearing blasting media. Personally, I just use a good canvas blast hood with a metal screen over a glass lens to prevent fogging from blown back sand.

I spent about 2 months off and on in '96 blasting the underside of a '68 Mustang prior to some bodywork. I just did the front end under the fenders and some of the suspension. It was very tedious work and very slow since I was using a 20 gallon portable compressor with a 2 1/2 hp motor. I got the job done, but I wouldn't do it the same way again. However, the results were great; you can't beat blasting for cleaning parts or getting rid of rust.

Randy

You might try aluminum oxide and always wear a respirator. You can get away with using a suction blaster, but a pressurized unit works best. How big of a compressor are you using? The bigger the nozzle on the blast gun, the larget the pattern, but the more cfm is needed. I blasted my entire 70 cuda body with plastic media. It had 6 layers of paint!! It took forever with an 80 gal 8hp 2 stage compressor and a 100lb pressurized blaster. It was like painting a house with a 2" brush. I did it, but it took a long time. You can get several recycles with the aluminum oxide. I think it's safer than sand..................................170bcuda

Randy, you're the new guy and you seem to want to be involved, and you're more than welcome to do so. But recommending gasoline as a wash solvent is so far off base......................... You're free to do so, but for anyone else reading here DON'T DO IT!!!! I've been around buildings that went up in flame as a result of using gasoline as a wash solvent. Both of them were service stations. One the kid was using it to get grease off the floor, the other a guy was washing parts with it. In both cases there was a pilot light ignition source (if you've got a heater, furnace, water heater, gas dryer, anything else with a pilot light in your garage it's not good). In both cases people were burned to death. In the parts washing incident a neighbor saw and heard the ignition, got his video camera, and taped it. The two guys in the shop were moving around, then sat on the curb of the station. Their clothes were burned off, their skin was red and brown. They didn't live 24 hours! Eerie to watch a tape, seeing these two guys walking around, seemingly calm. But knowing that when the shock wore off they suffered mightily for many hours. Sorry to be graphic, but there are many other solvents that are nowhere near as volatile as gasoline. Regardless, NONE of them should be used whereever there's a remote chance of ignition from an open flame, or the spark from any electric motor (drill, grinder, whatever). It's just plain suicidal to think otherwise!

As for the need of a respirator, absolutely. Read this link about silicosis; http://www.nlm.nih.gov/medlineplus/e...cle/000134.htm
the meat of it starts about 1/3 the way down the page. Yes, if blasting, a full hood on top of the respirator is essential.

Originally posted by Bob Parmenter
But knowing that when the shock wore off they suffered mightily for many hours. Sorry to be graphic, but there are many other solvents that are nowhere near as volatile as gasoline. Regardless, NONE of them should be used whereever there's a remote chance of ignition from an open flame, or the spark from any electric motor (drill, grinder, whatever). It's just plain suicidal to think otherwise!
\

I can speak from personal experience about the pain of being burned. When I was 9 yrs. old my brother and I were messing around with gas. We had a can of gas burning in the middle of the farm yard. My brother got the idea to put it out by stepping on the top of the can. I don't remember exactly how but the gas sprayed me. I had first and second degree burns over my face and hands. Fortunately it was winter time. I was wearing a parka so that's all the skin that was exposed. Once the shock wore off the pain was unbearable. Took several weeks to heal. I was fortunate enough to not suffer any scarring even tho my folks didn't recognize me when they came home later that night. The only evidence now is when my face gets real cold (Red) in the winter you can see the scars. I have a real respect for fire and gasoline now.

Here is a list of what I like to go by. It will be long for me to type out but will help I hope. Glass bead is the best for cleaning aluminum, brass, and die cast.
Aluminum Oxide- Best to remove carbon, rust and paint and for paint preparation.
Silicone Carbide- Best for brazing and welding prep, and glass etching (frosting).
Walnut Shells- Best to use on tranny and engine cleaning.
Poly Abrasives- Best to use on paint removal with no rust.
I say use either Poly Abrasive or Aluminum Oxide. Silicone Carbide may be too heavy to use and will leave the surface pretty damn rough.
Hope this helps you decide on what to use.
Oh and good PSI for this is on the glass bead around 60 PSI, Aluminum Oxide 80-90 PSI
Silicone Carbide 80-90 PSI
Walnut Shells 80 PSI
Poly Abrasives 35-90 PSI

Originally posted by pro70z28
I can speak from personal experience about the pain of being burned. When I was 9 yrs. old my brother and I were messing around with gas. We had a can of gas burning in the middle of the farm yard. My brother got the idea to put it out by stepping on the top of the can. I don't remember exactly how but the gas sprayed me. I had first and second degree burns over my face and hands. Fortunately it was winter time. I was wearing a parka so that's all the skin that was exposed. Once the shock wore off the pain was unbearable. Took several weeks to heal. I was fortunate enough to not suffer any scarring even tho my folks didn't recognize me when they came home later that night. The only evidence now is when my face gets real cold (Red) in the winter you can see the scars. I have a real respect for fire and gasoline now.

I light the garbage with a tiny amount of gasoline, 2 stroke gas, I put it in a pump oiling can and put it on newspaper then light the part of the newspaper that's not soaked in gas and run. I also use a pump oil can for squirting gas into the carbs of engines, like my lawnmowers or my '67 Falcon 1 time when it just woulden't start because it had sat in the cold weather for a month without starting. I have never been cought on fire due to a gas explosion but, an alchahol accident, yes, I was working in chem class, we were firing off spud guns we had just made with alchahol, my gun was 6" and was a 2" pvc pipe with a spray can top jabbed on the back, it was originally a chemical candel so it had a spray can top on each end originally, I decided to put the second top on loosely so it would shoot the top off, little did I know, the 1st top at the back, had ridden loose from the first exposion and, it blew out the wrong way, right at me. my shirt and hand and the floor and my shoe were on fire but, as the alchahol burns at a low tempurture and it was 75% alchahol, it actully burned ontop of my skin rather than burn my skin itself. I did get a very very slight burn on my hand, but it was so minor, I didn't even worry about it.

Originally posted by Matt167
I light the garbage with a tiny amount of gasoline, 2 stroke gas, I put it in a pump oiling can and put it on newspaper then light the part of the newspaper that's not soaked in gas and run. I also use a pump oil can for squirting gas into the carbs of engines, like my lawnmowers or my '67 Falcon 1 time when it just woulden't start because it had sat in the cold weather for a month without starting. I have never been cought on fire due to a gas explosion but, an alchahol accident, yes, I was working in chem class, we were firing off spud guns we had just made with alchahol, my gun was 6" and was a 2" pvc pipe with a spray can top jabbed on the back, it was originally a chemical candel so it had a spray can top on each end originally, I decided to put the second top on loosely so it would shoot the top off, little did I know, the 1st top at the back, had ridden loose from the first exposion and, it blew out the wrong way, right at me. my shirt and hand and the floor and my shoe were on fire but, as the alchahol burns at a low tempurture and it was 75% alchahol, it actully burned ontop of my skin rather than burn my skin itself. I did get a very very slight burn on my hand, but it was so minor, I didn't even worry about it.

Wow! Thats the kind of information that helps and prevent accidents from happening. Thanks to everyone for the information and I willn't use gas.
I do have 5hp compressor with and eighty gallon tank maintaining 15cfm @ 90 psi with 175lb tank pressure. I don't want to do the car just the underneath. I just have a problem putting new or rebuilt parts on grease rust and dirt, even if I am only mocking up the car before I take it apart again for the body and paint man.
Randy, I have found out threw first hand experience, that this is a very humblings site in a good way.

If you are going to use poly abrasives or plastic for blasting, do it at low psi. I mean like 7-15psi. with a pressurized unit. It you blast it with high pressure you'll atomize the plastic media into dust and won't be able to recycle it. It's not cheap either. Like all media used when blasting, its very dusty and gets into everything. ....................................170bcuda

Oh you guys! I didn't mean the fellow in question should use gasoline to clean off undercoating in his garage with a source of ignition close by. I didn't even mean he should use it outside with a source of ignition anywhere in sight. I just meant he should CONSIDER using an organic solvent like gasoline to wash the stuff off before he tries to blast. I just assumed (wrongly for a number of you, obviously) that he would be very careful with a flammable solvent.

I've personally known three guys over the last 40 years who were burned to death or killed outright in a gasoline ignited fire or explosion, so it's not that I've never heard of it happening before! They were all three careless and had fatal accidents; however, that doesn't make their loss any less deeply felt by myself or anyone who knew them. So yes, I'm well aware that many people have been horribly burned, or know someone who has, while using gasoline for any reason.

Specifically to Bob Parmenter: Yes, Bob, I am the new guy here at this website, but I ain't the new guy on the hotroddin' block. I've been working on internal combustion machinery since I was 7 and I'm 50 now and I've still got all my skin. I've been around gasoline at least that long, using it for fuel and a solvent, and I'm not just lucky, I'm careful. I also DO want to be involved; I'm a fairly reliable source of automotive information on many fronts due to my many years of experience in the field. But; your response was a little testy if not downright self-righteous. If this is not a forum(s) where experience and opinions may be exchanged freely without withering criticism from other members, then I need to know that right up front. Other than that, I submit to your rebuttal, and apologize to any other members who were offended by my perceived incosiderate concern for their safety.

And finally to TedIII, I'm sorry that I put that gasoline bit in there in the first place, I don't want you to jeopardize your safety in order to clean undercoating from your car. You do need to get rid of the stuff at least by scraping or you'll be forever and a day trying to knock it off with the blaster. And once again, please excuse me for intiating these burning horror stories as responses to your questions; it was truly not my intention.

Well Randy, as I said in my opener to you.............you're welcome to post at will. As for rebuttal, none of us are immune to that, it's pretty much the nature of the beast. Testy? I prefer curmudgeon.

There's no doubt that a lot of geezers have survived dangerous practices, myself included. Maybe it's a Darwinian thing. But just as we are all wont to share our mechanical experiences in the hope that we'll save the "younger or less experienced" some time/money/effort/angst, safety issues fall in the same vein as I see it. It's the ubiquitous nature of gasoline that makes it all the more dangerous. The old "familiarity breeds contempt" thing. While you've been mindful of the surrounding hazards when using gasoline as a solvent, far too many don't have a clue as to it's volatility when uncontained. I'm sure to you it's instinctive, or a function of your having learned appropriate respect at an early age from someone else. As you'll soon see, if you're not already aware, when you read some of the posts that come up you can't help but wonder why others haven't developed the same kind of "instinct". My concern was someone would have read your remarks, today or sometime in the future, and take them literally, without consideration of the unstated precautions that you would use. They may not have learned enough yet to put 2+2 together as it applies to handling gasoline. Sharing some of the potential pitfalls may seem "self righteous", I see it as a sensible precaution.

Again, welcome aboard.

I've used silica sand but had nothing but grief from the sand clogging due to picking up moisture from condesation in the tank.

Now I use a product called "Black Beauty" I think it's like a slag from the foundry process. I'm not sure but it doesn't clog like sand, cuts rust & paint and can be recycled. I put a big 20' x 50' sheet of black plastic on the ground to collect the stuff, then sift it through a screen for re use.

I get Black Beauty from the local ready mix / concrete products supplier.

Works GREAT!

As for getting the undercoating off. I place kerosene soaked rags on it, let it sit... then scrape it off with a putty knife.

Of course I do this all outside with good ventilation.