Sandblasting vs. wire brushing/sanding method?

T

Trekemeyer

Senior Member
In preparing the metal body parts for painting, I was told the method of sandblasting was harmful to the individual as well as the parts warping. The process of wire brushing/sanding and acid preparation was less damaging. Any opinions based on past experience using one process over the other would be appreciated.
 
How harmful blasting is depends on the media being used and the breather precautions taken. Damage to the item being blasted depends of the item! Thin metal such as body panels can easily be warped, heavier metal not so much. Some items are very difficult to clean the media out of after blasting. So, it is hard to make general statements about the best way to prepare an item as each can be different. Wire brushing will damage some items as will acid.
 
(Sand)blasting isn't just with sand (silica). Silica poisoning of the lungs is bad so it is best to use a mask with a fresh supply of air (not just a filter). Aluminum, glass, walnut is much safer to use.

But a good experienced blaster can clean a fender or hood without warping it. Brushing or sanding has not cleaned rusty metal like blasting (especially if you tried to lead it) and acid prep is hard to dislodge in folds in metal.

So you take your chances in any method.
 
I have done all methods and for me it depends a huge amount on the person doing the blasting. My favorite place just closed down last summer and the owner retired. This company did my 32 avatar rust bucket roadster and my 40 wagon. He was a sheet metal man before he owned a sandblasting company (plus he owned a 36 cabriolet and a 39 4 door). He understood what he was doing. He would turn down the air pressure and use sharp garnet to remove pant and rust and NEVER warp or work harden the metal. He was careful. Some places hire minimum wage guys who just want a paycheck and don't care what they are blasting. Fortunately I am done working with rust. I have a rust free 55 brand X convertible that another friend that does plastic media blasting can take the paint off but it won't remove rust. There used to be a Redi_Strip franchise in Seattle that I had a 34 sedan delivery body dipped. It did a great job removing all the rust but some chemicals remained in places like where door skins are crimped over and I was always repainting those areas as it would flake off after about a year. There is a place in Portland Oregon I can take things that does an acid dip and when properly neutralized by them leaves parts pretty clean. I have heard of parts being dented as they load too many things in their tanks some times.
However, no matter what method you use, you still should SAND the parts before you etch and prime them.
JSeery is right, no blanket statement can really cover it as there are too many variables.
 
I’ve found the damage to panels from sandblasting is improper technique, air pressure and media used. Like has been said......each way has it’s drawbacks.......Mark
 
There are safe ways with breathing apparatus to protect health. The severity of the job will dictate the method of prep. Sanding, wire brushing, even paint strippers are very time consuming. Doing yourself over long period no prob. Instructing paid service to do your pockets better be deep. There are more than a few blasting techniques, some less likely to damage, media blasting with nut shells, different hardness level of grits, the the most recent is wet blasting withe the different types of blast media. Pressure can be adjusted to meet the requirement as well. Higher pressure for substantial pcs less for mor delegate. Some type of media blast with post panel or section weld repair is typical in resto & Hotrod shops.
 
When I stripped my coupe,I removed as much of the paint that I could with paint stripper and a putty knife. Next I used a Harbor Freight abrasive wheel
(item # 60571) on a 10,000 RPM angle grinder to remove any residue. The wheel leaves very fine scratches and won't harm the metal unless you use too much pressure or hold it in one place too long. I used the sand blaster for nooks and crannies.
 
Every method has it's pro and cons and a lot depends on operator skill and knowledge. Even using something like a grinder or other high speed sander on a body panel can warp it if not done properly!
 
There are more methods of removing/stripping paint.
For example I removed the factory paint on my vehicle down to the red oxide primer using a hand held (home made) scraper that used a carbide insert. Then the remainder was removed using #80 grit discs on a DA sander plus a little hand sanding. The few rust areas were cleaned using a hand held grit blaster using #80 grit media.
 
Willit Stop said:
When I stripped my coupe,I removed as much of the paint that I could with paint stripper and a putty knife. Next I used a Harbor Freight abrasive wheel
(item # 60571) on a 10,000 RPM angle grinder to remove any residue. The wheel leaves very fine scratches and won't harm the metal unless you use too much pressure or hold it in one place too long. I used the sand blaster for nooks and crannies.
Click to expand...
Thanks for your information regarding purchase of the wire wheel. Very helpful.
Tom Rekemeyer
 
It's not a wire wheel.It more resembles a black rice cake and is polycarbide.Lasts a long time if you stay away from edges and will remove light rust.
https://www.harborfreight.com/4-12-in-polycarbide-abrasive-wheel-60571.html
I tried a little experiment and stripped a piece of painted sheet metal with the wheel on the grinder. Sprayed one coat of etching primer,one coat of sealer,two coats of basecoat and two coats of clear. It came out perfect.....no sand scratches showed through the paint.
The HF grinder was about $25 and the wheels were about $6 each.I don't remember how many I used to strip my coupe,but am sure it was less than 10.
 
dustless blasting is the way to go it actually cools metal it uses water with media . its costly but very efficient it needs 185 cfm @ 100 psi . i have one
 

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getting ready to have my 1940 Ford coupe painted. The local dustless blaster will blast the main body and doors for $550.00 the hood deck lid and fenders are already done
The cost of the transportation is about $400 round trip as I cannot blast at my home, Dustless blast can do this at you home if you have an open space
There is a rust inhibitor in the water that keeps from flash rusting for about 3-4 days
I think this is the way to go, just get rid of the excess media.
 
the dustless blaster sure seems to be a good thing. dont have one, but my experience here, i have been blasting at home, out in the country, for about 35 years. started out with a siphon pot which is about like using a pencil eraser. next i built a pressure pot using a 100lb lp tank as the base, and proceeded to kill my 3hp compressor. compressors can not run full time, they need the pause too cool. next i got a 5hp compressor, and would run the two of them together, that got me by for a while. all the while when doing this, the results where terrible when ever the pressure got down near 100, and worked good with the system full at 150, blasting a spot about the size of a quarter. next i got an old portable compressor on wheels, 50's thing, i forget what the heck it is, but the interesting thing here is that that machine never makes more than about 65psi, but blasts like hell compared to running the two wore out 3&5hps. its volume, not pressure that does it. next issue, warping. even though i have done many projects, for many years, and i always say "not this time, i'll be careful" i still warp any piece of sheet metal. on a body, or a cab, i like to do the things that are hard to sand, like door jambs, trunk gutters, etc, but even then, if i venture out to far i find warps when its time for blocking primer. i had a friend years ago who played with high dollar old porsches, and he had a guy who could do whole doors and hoods with out wrecking them, but i never knew how. next, cost. they mine the silica sand near me, so years ago i could go to the plant and buy 100lb bags for half what they cost at the store. if you had a way to load it in bulk it was darn near free it was so cheap. they cut me off about 15 yrs ago, wholesale only now. when i blast i do it on a hill near the shop, gravel road that goes down to my junk yard. one heavy rain and the mess is gone. so, some might think i have it pretty good, but the truth is now days i hire a local guy that buys sand by the truck load, and has a machine out of the space age. i cant spend 75 dollars on sand, 5 gallons of gas, switch some battery's around, clean the carb, hammer on the starter, finally get the thing running for its once a year job, spend a half a day to to what he will charge me 25 bucks for. small parts go in the blast cabinet with glass, and i have played with molasses and electrolysis , not tried citric acid yet, but its on my list. best is to buy parts that didnt live in a swamp
 
I have the small unit DB 150 and it is great but it sure costs a lot. You also need a compressor capable of doing 187 cfm. I bought a used Ingersoll rand diesel compressor and it works great. Fast, no heat warpage but it does cost lots of money.
 
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