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sandblast question

4K views 24 replies 11 participants last post by  swvalcon 
#1 ·
I have access to a 100 cfm compressor and own a clemco 60 resperator. i have several items to blast. Is it worth the money to rent a clemco or marco blast pot? I have a cheap hf blaster and am not sure if it would became a weak link in the blasting procees. With a 100 cfm compressor what would be a good nozzle size to blast with using 30 grit? And last of all roughly how many pounds of sand does it generally take to blast a mid sized car assuming no filler and 1 coat of paint.....Steve
 
#2 ·
My advice is DO NOT sand blast the body panels. You can and likely will destroy one or all the panels. And we aren't talking about "Damn I have more work to do" kinda damage, we are talking "#^@& I HAVE TO BUY A NEW HOOD!" kinda damage.

Unlike the common myth that the sand blasting is causing heat to warp the panels (I too thought that for yeas. You are blowing air on the panel so it actually gets cooler, try it, I have, after sand blasting the metal is cooler.

The warpage is caused by "Mechanical compression" that being each of those pieces of sand is like a tiny hammer putting a little dent in the surface of the metal stretching it. The top surface of the metal gets larger than the lower layer and it warps.

Can you sand blast sheetmetal without warping it, yep you can. I don't see a need to see when it works and when it doesn't personally, I am going to find another way like chemical striping or sanding it off with an orbital sander which creates much less heat than a "grinder". But I wouldn't be sand blasting it.

Brian
 
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#3 ·
I was looking at possible chemical stripping of the wide open areas like hood, door panels and such then using sand blasting on the areas like firewall, doorposts. I know stripper sux to get in seams. Do the professional blasting outfits have a techniqur to avoid panel distortion?
 
#4 ·
I've even had pro's ruin panels. I don't know, I think it is more about what material you use, but sand is a no-no. There are a couple of guys on here that know a bunch about the subject let's see if they respond.

On the stripper,that I have done a ton of and have a few tips. The trick to stripper is you simply mask off what you don't want it on just as if you were painting it. Here at work we will strip the roof of a year old car leaving not a mark on the rest of it, simply my covering the car in plastic, exposing the roof by cutting it out and then adding some masking paper over the top around the top just for good measure. After it's stripped being very careful to peel the paper off as to not touch or drip it on the car and wham, done deal bare metal roof.

Seams and such you always want to cover with duct tape then after it's stripped you remove the duct tape and remove the paint and gunk in the seam with a surface conditioning disc .....



Or a "clean and strip" disc.



They work WAY better than a wire wheel.

But this is the norm, to cover up what you don't want stripped. I have even done complete cars that were assembled (no chrome and handles and stuff though) where all the door, fender, hood, trunk seams were duct taped and any other holes like antenna and handles and locks. Then remove all the tape and sand off the remaining and wham, bare metal car.

One thing I can't stress enough, if you can't really jump on this car and knock it out in a day and sand it and get it into epoxy primer I HIGHLY recommend you do a panel at a time. It takes a little more time but you don't get overwhelmed. it is VERY easy to be overwhelmed by a bare metal car sitting there. And you just can't walk away until you feel like it. So doing one panel at a time getting it back into epoxy primer then moving onto the next is a recommendation.

Brian

Brian
 
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#22 ·
On the stripper,that I have done a ton of and have a few tips. The trick to stripper is you simply mask off what you don't want it on just as if you were painting it. Here at work we will strip the roof of a year old car leaving not a mark on the rest of it, simply my covering the car in plastic, exposing the roof by cutting it out and then adding some masking paper over the top around the top just for good measure. After it's stripped being very careful to peel the paper off as to not touch or drip it on the car and wham, done deal bare metal roof.

Seams and such you always want to cover with duct tape then after it's stripped you remove the duct tape and remove the paint and gunk in the seam with a surface conditioning disc .....

But this is the norm, to cover up what you don't want stripped. I have even done complete cars that were assembled (no chrome and handles and stuff though) where all the door, fender, hood, trunk seams were duct taped and any other holes like antenna and handles and locks. Then remove all the tape and sand off the remaining and wham, bare metal car.

One thing I can't stress enough, if you can't really jump on this car and knock it out in a day and sand it and get it into epoxy primer I HIGHLY recommend you do a panel at a time. It takes a little more time but you don't get overwhelmed. it is VERY easy to be overwhelmed by a bare metal car sitting there. And you just can't walk away until you feel like it. So doing one panel at a time getting it back into epoxy primer then moving onto the next is a recommendation.

Brian

Brian
What's the name of your stripper? Sorry, couldn't resist. Honestly though, what brand of chemical stripper (and source) do you prefer? I've used the stuff from Home Depot before on tractors. And what is your process for making sure the stripper is neutralized and ready for primer. Thanks
 
#5 ·
The rule is sand where you can and blast where you must such as on flanges and door posts where sanding is difficult..i use the 2 inch rolocks and can get into some amazing tight spaces with those and if I need to blast I use vitrogrit in an 60/80 grit and run 40/50 psi and have not issues..blasting the whole car takes lots of media and makes more of a mess that I want to deal with..

Sam
 
#6 ·
what grit would you guys recomend for sanding with a da? I definitely dont like the mess involved with sand either. I definitely like the idea of sand where you can and blast where you must. Taping seams is a good reccomend. I dont mind combining blasting, sanding and chemical stripping. 1 size doesnt fit all. frames and such I will definitely blast
 
#7 ·
Dont know if its rite or wrong but it what i was taught , if you use stripper we use aircraft stripper ,cover the panels you have stripper applied to and not working with plastic helps to keep from drying to soon ,dont get to far ahead cover one panel while working the next .as for sandpaper i use 180 to remone paint if you use finer grit 320/400 to strip paint it will cause heat that you dont need.
 
#11 ·
paint removal

There is a lot of info here on hotrodders in the Wiki Section. , My willys had about 6 coats of paint and I scraped the top layers off, a lot of chips, no gooey mess until I got down to the bottom layer and used stripper. I also use my 3500 Psi pressure washer, to remove the stripper-paint that doesn't come off easy with a scraper. It will remove a lot of paint just slower, I also have a wet blaster from northern tool for heaver metal parts, frames ,axles, etc. water and sand, NO dust, just a wet mess, I had my nash roadster blasted by a guy the restorations guys use. He knows what he is doing and doesn't warp panels but cannot get out all the pits in sheet metal.
 
#13 ·
check with your pait supplier BEFORE using soda blaster NO paint company i know of will warranty wheir paint if you use soda it leaves film that effects paint .You can use a Dustless Blaster that uses water and recycled glass ,check on web. Your state might be different but i dont think so,You can strip an entire car under an hour.
 
#16 ·
My painter has never complained about me bringing him shells and body parts that were soda blasted,been using it for maybe 10 years now without issues.
Back when I used to have parts chemically stripped by a shop who would dunk them in a big vat full of nasty chemicals we had lots of problems with paint sticking because parts would come out too smooth and sometimes it was a pain in the *** to get it out of hidden areas.
We used to have to sand every square inch of a part inside and out just to get primer to stick after the chemical stripping:pain:
 
#17 ·
He is referring to the paint manufacturer, not a painter. The paint manufacturer, every paint manufacturer I know of says DO NOT use soda stripping.

And like sand blasting it "can" be done, there are people who have sand blasted sheet metal for years without destroying it, so it can be done. But the overall majority of times it causes irreversible damage (or close to irreversible).

So what is happening is your painter is getting around this very difficult problem of the soda embedded in the metal, he is neutralizing it properly. If he didn't you WOULD know, we are talking total and complete catastrophic failure.

Brian
 
#18 ·
Soda is alkaline in nature and most primers are acidic so if any soda residue is present it will neutralize the acid in the primer and then the paint does not stick..Some guys have somehow escaped this issue but a lot have not and tha tis why we do not recommend soda.

Sam
 
#20 ·
When some experenced painters swear by a product that I am having trouble with, I have to assume it is a problem with some part of my procedure.

But if there are several others that also have trouble with the same product, then I my have to decide if the benifits of that product are worth the effort to me, or if there might be another product that will give me what I am looking for.

And it is usually just a matter of learning how to use the product properly.
 
#21 ·
I've stripped plenty of cars. It seems to me that almost all strippers today claim to be "aircraft" strippers. Well, I've stripped and painted a few airplanes, also. My best advice would be to tell you not to go cheap on the stripper. Just like anything else, you get what you pay for. I use JASCO Premium Paint & Epoxy remover. Cost is about $31.00 a gallon at Lowe's and it works very well. If you apply it according to the directions and what's been said on this thread, you should do well. After stripping I use 80 grit to clean it up with a random orbital. Just remember to give the stripper time to do what it does. And, as mentioned, don't let it dry on the panels. If it does you'll end up loading up a lot of sand paper trying to get it off. I usually wash mine down with lacquer thinner after scraping.
 
#25 ·
I've worked on two cars in last year that had metal damage from sand blasting. Only sand blast in door jams and places where it wont show. I did do a little blasting on the rear fenders of my 64 stude but they are really thick and I was very carefull with it. I wouldn't use soda either. Most of my paint stripping is done with 40 or 36 on a da both 6 and 8".
 
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