Media Blasting and Surface Prep

[DJ194950]

I did my 50 Suburban by sandblast in my back yard on a concrete slab only slightly bigger than the car.

 

$20 total in sand? I would have had to buy at $1 a 60 lb. bag to do that.

 

Used at least 20+ 60 lb. bags of silica sand 30 grit  ($4.00 at bag 10 years ago)  to do the body in and out, frame complete (body off) and underside of body.

 

Lot of work and a large pile of sand to get rid of with about 40-50 lb. per week in the garbage can!   Live in the city.

 

My compressor is 60 ga. tank and a 6.5 hp motor. Runs 125 psi max. 40 lb. pressure pot from Harbor Freight. Used full pressure, but it does drop as being used and ran most of the time while blasting. Nozzle tip size make a big difference on coverages and psi required. Only your own experience will tell what works best with your setup. Buy plenty of replacement nozzles as they wear out and cause a lot of wasted sand and speed!

 

Have fun and plenty of hydration for your breaks!

 

DJ

[austinsailor]

Plymouthy know what he speaks. I've done several cars and can add little to what he's said, except it's not the heat that kills you, it's the peening action of the sand. You're basically hitting it with a million of little hammers. Add the heat from all that pounding and you get into trouble. Solutions are less presssure - I use about 80 lbs or so - go lightly, and hit at more of an angle so the peening action isn't so severe, and move around so what heat you might generate has time to disapate.

 

I fail to see how wire wheels and sandpaper can get rust out of the bottom of a pit, or down in crevices. Blasting can get it all, no matter how uneven the surface is. It you can hit it, at least. Insides of frames and doors can be tough.

 

Once you've blasted, you have a good surface to hold paint. It has to get a bite and that leaves a pretty good place for a bite.

 

I used about 50 to 100 lbs an hour or so, I'd say. Using the silica sand that Home Depot sells in the midwest, not sure they sell it nationwide, as it's mined nearby.

[Jocko_51_B3B]

I'm planning on using a newer process called Dustless Blasting. You can Google it.

[Dan Hiebert]

Lots of talk on sand blasting, I can't add any more to that conversation, but you asked about primer, too.  There has been discussion on this topic in this Forum, so a search will be beneficial.  That being said, self etching primer is supposed to be best for bare metal, although I don't know the mechanics of it.  Media blasting will also provide an excellent surface for any type of primer to adhere to.  Any acrylic primer will need to be sealed if your not going to top coat the car for a while, as primer will attract and hold moisture and you'll just end up with a rusty car again.  I used urethane primer on the last car I painted.  Doesn't need to be sealed, and I was impressed with the coverage and finish.  Its also compatible with any type of paint.

[jeffsunzeri]

The many and varied responses to this thread are good indicators of just exactly my point when I recommended not blasting your car. If there are "secrets" and learning curves, and numerous opinions on media, pressure, etc. then it's not a good process for an amateur.

The main thing is that we are caretakers who will not live longer than our MoPars. Most in the hobby/business for an extended period of time have had to deal with the effects of a bad, but well intentioned, blasting job. Blasting gone bad erodes the metal unevenly, and may also warp panels. Neither of these effects can be brought back to new condition, thus potentially relegating the part to the scrap heap. For every amateur success story, there are an equal number of horror stories. Those horror stories result in good parts being turned to useless trash.

Professionally done under the right circumstances on the appropriate panel, blasting is a great solution. Those are a lot of qualifications. There are many alternative paint, rust and scale removal methods that are much less aggressive and more appropriate for the backyard mechanic that carry much less risk than blasting.

DPO = Dreaded Previous Owner

[RobertKB]

I had my entire '38 Chrysler media blasted by I believe crushed walnut shells. Might have been sand for some parts. Frame was done with sand. Results were wonderful for both. I like blasting best as you can have the body dipped but that has its own problems down the road. Sounds like sand blasting will be fine if done properly and being aware of potential problems.

 

In the 10 years the car has been on the road I have challenged people to find a single wave of warp in the body work. As the car is black it will show any imperfection easily. Never had anyone pick up a single flaw. This speaks well of the body man but also, I believe, to proper blasting.

 

 

Edited May 20, 2015 by RobertKB

[Jocko_51_B3B]

I just had the running boards and a bunch of smaller rusty structural and engine parts off my '51 b3b blasted using 40-70 screened crushed bottle glass. They seem to have turned out pretty well. Supposedly CBG leaves less than 2% embedded material which sounded good to me, but who knows. Anyone else used crushed bottle glass? If so, did it turn out OK? I wonder if there is much difference between CBG and plain old sand.

Edited September 8, 2015 by glenn777

[bluebanshee]

Soda blasted all body parts except the cab. As already mentioned it will not do well with rust but will take a little off.

[JD luxury liner]

I use Black Diamond,a Tractor Supply blast media, less dust & cuts rust very good. I made a blast cabinet out of a plastic 55 gal drum for smaller parts.

[Jocko_51_B3B]

I'm having a local shop blast and prime the sheet metal on my now dismantled '51 B3B. The results are turning out perfectly. The Dupont media contained in the bag in the attached picture is a finely ground natural mineral called staurolite. I like to get down to the nitty gritty (no pun intended.)

 

http://geology.com/minerals/staurolite.shtml.

 

[Jerry Roberts]

I just had the running boards and a bunch of smaller rusty structural and engine parts off my '51 b3b blasted using 40-70 screened crushed bottle glass. They seem to have turned out pretty well. Supposedly CBG leaves less than 2% embedded material which sounded good to me, but who knows. Anyone else used crushed bottle glass? If so, did it turn out OK? I wonder if there is much difference between CBG and plain old sand.

 Well , glass is made from sand . 

[Jocko_51_B3B]

I switched from using the crushed bottle glass to Dupont Starblast because it doesn't rough the surface up as much. But both were OK.

[stan's52]

Sand blasting does warp parts. At work I had some machine access panels blasted. They

warped which didn't matter, when they were attached to the machine they were ok. That

being said. I have been using a small sand blaster on my 52 coupe to get rid of serious rust pockets. from what I understand the silica is not good for the body. I usually used a dust mask, which is said not to be used for sand blasting. I guess it is better

than nothing. This time I used a shop vacuum discharge side for my air supply. I

removed the dirty filter, cleaned the vacuum inside real good and wrapped a rag around the filter area. I attached a hose to a old welding helmet, installed some heavy material around the sides. Now I have a fresh air supply. I still wear a good quality dust mask under the helmet. Works for me. Stan

[Plymouthy Adams]

it takes high pressure and high sand flow to generate the heat needed to warp a panel....this is the rule out for a commercial blasting facilities for the most part..time is money..less time to blast the more money they have the potential to make moving next batch in...they usually DO NOT CARE

 

doing it yourself, controlling pressure and flow and having the good sense and patience to come back to a stubborn area on repeated visits so not to heat a panel will garner excellent results....keep moving...I have sandblasted a number of cars and panels now without ever a problem..again just use your head...and if you do not have the time to do it properly, then...my advice is not to mess with a sandblaster at all, or be prepared for the results of your haste...you are in control.

[casper50]

I've also done 2 including this coupe.  Works well.  Just a dirty slow job.