Soda Blasters

Do you want to build one? The first thing you will need is a BIG compressor.

Then it's simply the same type of gear used in sand blasting. A hose, nozzle and syphon tube sticking into a pot of baking soda.

I hire soda blasters to remove graffiti from delicate surfaces, or brick or stone work buildings. It's slower than sand, but doesn't remove much substrate.

I'm told it's THE way to remove paint without damage to the body.

I've done a substantial amount of paint removal, there is no fun, easy way. If you could give some more details on what exactly it is you're doing, I might be able to help. Different situations call for different methods. If you've determined that this is the way to go, it's been my experience, that it's almost always less expensive to buy a unit, (used), than it is to try to acquire parts and build your own.

I,m rebuilding an old (1964) Landrover 2A, the bodywork is aluminium and the existing paint is in poor condition, Flaking etc.

Get one of these, it's called a suction blaster. It uses play sand for sand boxes. About $20 US. They work great. Hook up your compressor, stick the suction tube in a bag of play sand and go. Make sure you use a respirator while using, not a particle mask. The play sand is fairly fine, and won't tear up the substrate. Do some experimentation on the inside of a fender, you'll be a pro in about 10 minutes. The sand must be dry.

There's a considerable difference between sand and soda. I'd definitely use soda on an aluminum body.

I don't see any reason why he couldn't drop the pickup in a bag of soda. It comes with 4-5 nozzles. I think it would be worthwhile to give the sand a try, though, a lot cheaper. I use mine at least a few times a year, with a little practice I think it would be fine. Just have to get air pressure dialed in and distance of the gun from the surface. I'm assuming he's going to refinish the car. All automotive primer/surfacers are designed to fill in minor imperfections, some minor pitting wouldn't be a problem.

A picture is worth a thousand words. I just hooked up my unit an ran screened play sand through it. Worked great. The blasted surface is completely smooth to the touch and has a frosted look. This would indicate that it is pitted, but on a microscopic level. This is actually desirable, and will help in the adhesion of your primer coat.

Be a little carefull with blasting aluminium with sand or grit, too much energy imparted to the surface makes is bend. Soda, alumina, even cement are much gentler. Dry ice blasitng is very good, slow and expensive.

As long as we're here, a few tips on painting aluminum. You don't want a polished look, it's going to have to be abraded anyway before painting. This is typically done with a dilute muriatic acid wash and rinse. Also, aluminum is not typically used for auto bodies. Make sure the primer is made to adhere to aluminum, and is compatible with the top coat. A google search on aircraft coatings may yield some information. I'd hate to see you do all of that work, and have paint coming off in sheets. This happened to both Ford and Chevrolet. They started using galvanized body parts, and switched to a primer made for galvanized metal, finishing with traditional top coat. They found out later that the top coat and primer were not compatible. Everyone here in the states has seen the pickup trucks with the peeling paint problem. Not pretty. The picture above is a properly prepared surface for painting. Wash off with water to remove dust and wipe everything down with denatured alcohol before priming to remove surface contaminants. Wear latex gloves for wipe down and painting to prevent skin oils from getting on the surface. Above all, have fun!

He'll need to acid etch and use a (probably chromate) conversion coating prior to paint.

http://www.ronjoseph.com/painting-aluminum.htm

I can't speculate on what paint system to use on aluminum, there are some tried and true methods, but coating technology is constantly being reformulated and improved. You might be able to find a kindred spirit over at Land Rover to give you some help, or maybe post in Chemical & Material science on here when you get to that stage.

Norm,

Here you are Norm, local and ready to drive away

http://www.asbsupplies.com/photos.html#

I've heard of a technique that uses dry ice as the abrasive in the sand-blasting process. The advantage being that it evaporates so there is a lot less mess. It may be expensive and not diy, but worth a look maybe.

Came across this how-to-do-it article last week, but haven't yet tried it - and on the same day I followed a van down the motorway with Soda Blast Cleaning emblazoned across the utility (for graffitti and usual commercial cleaning on a water blaster scale). The lesser environmental impact probably provides a more efficient clean-up after the work compared to solvent and chemical type cleans.

http://www.aircooledtech.com/tools-on-the-cheap/soda_blaster/

In my experience sand blasting flat panels of metal makes them bulge out towards the blaster. There is now a Diamond blasting that is even kinder than soda.

That's a fact. The metal is expanding as it is being hit by the sand particles. Great care must be taken to not warp the workpiece.

I should have mentioned, that I'm using a fairly small compressor and blasting at about 115 psi, it's just enough to remove the paint, but I can shoot it directly at my hand and it doesn't do any damage. It might pay to get a sacrificial piece of painted aluminum and do some experimenting. I think any type of abrasive media would go through the gun above.

I just watched some utube videos on soda blasting. They are running at super high pressure. Soda would be ineffective with my technique. The warpage that is associated with sand blasting, I think is referring to industrial type blasting. My method is time consuming, ( we're probably talking about an hour to do one fender), and barely qualifies as blasting, it does work though, and it's cheap. I'd be really surprised if it distorted the metal, but I've been wrong before. I'm using a little 4hp compressor with a 30 gallon tank, 120 psi max.

Wet blasting works well (water blast and sand).

Another possibility. I don't know if there are any of these in your area, but there are places that do nothing but strip finishes. Pieces are dipped in a vat of chemical stripper and washed off, it's usually pretty reasonable in cost also.

Hi guys, Thanks fellahs for the your input, and despite the fact that I have two compressors sets, hooked up in parallel, I'm not having much success. I've tried soda and fine sand but no go, the soda works incredibly slowly, and I have no joy with the sand. I've tried large hoses, on the premise that airflow may have been a problem, and pressures up to 100PSI with no success. So I've thrown the towel in, and resorted to manually removing the paint with sand paper etc. but of course it's a long process. So there we are. Thanks again fellahs, Norm.

Sorry to hear that norm, personally, I would bite the bullet and buy some aircraft stripper, brush it on and wash it off, ( make sure it's water rinse), and call it a day. Hand sand any remnants. Good luck with your project!

g'day Normbourne. Don't give up yet. I see you are in OZ. I bought a small sand blaster gun with a hopper on top for only $30. I haven't tried it yet but it is available at TOOLMART. I will get some more details and post again soon.

After resorting to the time honoured way of paint stripping, vis manually, I am not yet 25% through it, and to say that it is peeing me off, would be to say, putting it mildly, a gross understatement...! The paint is coming off OK, albeit slowly, but obviously the aluminium sub-strate is sustaining damage also. Accordingly I am once again, investigating the soda blast principle. I've just been watching a couple of videos, and there is one which appears to be using water at the same time, but what did strike me, was that the size of the nozzle appeared to be fairly small. Perhaps that's where I was going wrong....??? I was using an old drenching gun, the nozzle of which was in the order of 10mm. Does anyone have any thoughts on this ..? Norm.

Hi Norm,

I was going to sugggest before you returned to the time honoured physical stripping that it may be worth persevering with the blasting technique. You are really looking for velocity rather than volume and the compressed air with the tube is only acting as your rough resemblence of a venturi. I think you will improve the result with a smaller tube and may need to experiment with slightly different angles of insertion into the carry tube.

It may be beneficial to experiment with a bucket of water in place of the soda ash and the settings which give you the higher flowrate of water from the bucket should give a guide to the optimum achievable.

I noticed in a Supercheap Auto store this week, a kit just for the purpose, using sand. For what it's worth, the pic may be helpful for your experiments.

Okay guys, bought the blaster from super cheap, a couple of bags of garnet, and we are away....!!!!! Takes awhile but certainly the way to go. Thanks for all the ideas lads, well done, and so we richochet to our next crisis, thanks again..!!