Sand blasting and chemical stripping is by far the quickest and surest way of removing ALL the paint, rust and other junk from your restoration. You can elect to do it yourself or have it done professionally. I chose to sand blast my restoration myself and here is my story...
I had been struggling many months trying to remove the finish and rust from the sheet metal on my TR4A, using wire wheels and my 3/8" drill. The planets came into alignment one day when I was at the Harbor Freight store buying more wire wheels and I saw a 40# pressurized sand blaster on sale for $80.00.
This process led me from the wire wheels on drills, to paint remover, and finally ending up with my sand blaster. The sand blaster is by far, the only answer to me. I went from spending more time removing the finish to having to carefully plan when I was going to sandblast so I had enough time to prime the striped surfaces before they rust! I never thought I would have to worry about that!!
There are four basic considerations you must resolve to use this technique;
The Sand Blaster
There are a couple of different types of sand blasters. The enclosed cabinet type and what I would call the "free air" types.
The Air Compressor
The air compressor needs to be big enough to provide sustained air pressure to the sand blaster. My compressor is rated at 8.6 scfm @ 40#, 6.4 scfm @90# on a 30 gallon tank. It has a 6.5 HP, 110 VAC motor which I think is the upper end of the 110 VAC motor selection. You need to consider running a separate 20 circuit breaker for your compressor just to be safe. If I had it to do over again, I would have spent the extra money on a 220VAC unit. Mine is about as small as you want to go. It keeps up with the sand blaster OK but it has to run pretty much all the time.
Media selection is very important too!
Glass beads do a great job on removing paint and light rust. They do an especially good job on aluminum castings. When you are done, it will look like you have a new casting. This will be great for the IRS swing arms and the intake manifold. On heavy rust it isn't as effective as Aluminum Oxide or Black Beauty. You can expect to pay anywhere from about $1.00 per pound to $.50 per pound. You can strain and re-use it several times. As far as I know, as long as you use a good respirator, you are safe from any long term health issues.
Aluminum Oxide is great for removing thick paint and heavy rust. I used the 90 grit pellets. The final finish is rougher than the glass bead finish, kind of dull. It really takes paint well. The primed surface is smooth and clean. You can strain and reuse Aluminum Oxide many times thereby reducing the overall cost of the media. You can pay about the same per pound as Glass Beads. Same story on the respirator too.
Black Beauty is a coal slag byproduct. It comes in three grades, extra fine, fine, and medium. It is actually the third type of media I have tried. For general paint and rust stripping, I just can't find anything that tops it. I usually pay about $6.00 per 100# bag which is always good! Secondly, it cuts the rust and paint about as good as the aluminum oxide. I can re-use it several times. It is not any more or less messy as any of the other media.. Unless you have a specific preference, like cleaning aluminum I would use the Black Beauty. I found it at a building supply house that specialized in masonry products.
Silica sand is another inexpensive way to go but there are some health issues. I haven't personally used this product although I was ready to. It costs about $6.00 per 100# bag also. It is basically white beach sand. I have heard the results are good. There are two issues that stopped me from using it. One is that it breaks down very easily so you only use it once. The other reason is the dust is very bad for you. Ever heard of silicosis?? Also, if it is beach sand wouldn't it still have salt in it?
Containing the mess
I am currently doing all the sandblasting in my garage. Care must be taken in protecting everything in the garage as no matter how careful you are, there is going to be a film of dust over everything. I purchased a few cheap tarps and some 1/2" electrical conduit and made up some curtain which I hung around the car during the process. I always sweep up carefully after each use. This is all strained through fine mesh strainers and stored in plastic buckets for the next use. The straining process also removes a lot of the dust created by the ground up paint and rust.
Here is my sand blaster. Like I said, I bought it at Harbor Freight for $80.00 on sale. It came with a funnel you see in the picture, a cheap hood, and a small selection of ceramic nozzles. All in all, not a bad bargain if I do say so myself.
There are 3 valves on the unit I have.
This is the main air valve to the system. This particular sand blaster came with it's own air dryer which you can see right behind the main air valve. I would definitely recommend a second dryer but I will go into that later.
Looking at the back of the unit, you can see the sand air valve at the top. This valve adjusts the volume of air to the blast nozzle and the lower sand valve.
This is the lower sand valve. This is a very important valve. This one is used to regulate the amount of sand being forced into the air stream.
Sorry about the wash out of the nozzle picture...
Updated Operation Suggestions
After using my sand blaster for awhile now, I humbly recommend the following procedure to get good results from your sand blaster. I take no responsibility for how someone uses these instructions!
Having said that... There isn't much of a recommended operation instruction other than what each valve does. After using it several times I offer the following recommendations.
Getting the air dryer than you know
One of the first things you notice about your sand blaster is that it is VERY SENSITIVE to MOISTURE. What will happen is that you will start in and it will be working away for about 10 minutes and suddenly, no media.. The problem... moisture. The single dryer that comes with the unit is not enough.
Here is a little lesson in physics that I learned the hard way. As the air compressor builds up pressure, the air is warmed. The warmer air becomes denser, which allows it to carry more moisture. Also another little tidbit of information. The warmer the air is, the less efficient the dryers become. My first thought was to add a second dryer. That improved things a little in that I could run about 15 minutes before it clogged up. It would degrade about 3-4 minutes every time I cleaned out the clog until I would just give up.
Then I thought if I could cool the air before it went into the dryers, maybe that would help.
Backyard Air Chiller
I ended up picking up 20' of 3/8" copper pipe and coiled it up so it would fit into a 5 gallon bucket.
Here it is.. This is plumbed in line between the air compressor and the first dryer. I filled it up about 1/3 with water and then put 20# of ice on top of that. It lasts about 2 hours until you need more ice.
This solved my whole clogging problem. I can run the tank try of media every time.
1. Media... Unless you have a special reason, use the Black Beauty media. You will save money and
1. Do all the stuff above first..
7. Open the valve on the nozzle and leave it open all the way. This is not where you control the media. You control the media with the sand valve. I know it sounds weird but it helps to keep the black hose from filling up with sand. (Kind of like a bad sinus condition if you think about it.)
8. Put on your respirator, gloves, hood, and long sleeved shirt.
Sand Blasting Trouble Shooting
If the sand stops coming out, there are two usual problems. Either there is too much moisture in the tank, or the tank pressure has dropped too low to force the media out the bottom of the tank. Bleed off the dryers and make sure you have ice in the condenser. If that doesn't do it try this next.
Close the Sand Valve, then the Air Sand Valve. Open the main air valve and let the pressure recover to about 70#. Now, crack open the Air Sand Valve just a little, then open the Sand Valve. This should force any blockage out of the Sand Valve. Then, open the Air Sand Valve up to the 7 o'clock position again. The problem is that the sand blaster tank pressure slowly drops if the compressor isn't keeping up and eventually the pressure isn't high enough in the sand blaster to force the sand out. By using the procedure above, the sand blaster tank pressure can recover enough to force the blockage out. You may have to play with the Air Sand Valve position a little as the tank empties. You should have enough media in the tank to run about 15-20 minutes.