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Don’t buy this pot.

June 1, 2013
Piece of junk

Piece of junk

I bought a sandblast pot from Harbor Freight. I recommend you don’t.

Learn from my lesson…

After meeting with masons on the roof about tuckpointing the tall parapets, they requested that all of the old tar and asphalt covering the brick be removed. This would allow them to see the condition of all of the old mortar joints, because we suspected that the majority of the wall joints were in really good shape and did not need to be replaced. Otherwise they’d have to quote their work assuming that all joints need to be replaced. After debating powerwashing vs. sandblasting, we decided the sandblasting would be the least messy.

Having done a lot of sandblasting of car parts back in my youth, I figured I could save some bucks and do it myself. I looked at rental units, then researched a variety of large capacity models, and then decided I’d buy the largest setup at Harbor Freight. After all – it met my #1 Rule for shopping there: Buy nothing with a motor. (and I already own an excellent large compressor; birthday gift from Sue…)

I also bought: deadman valve and ceramic nozzle set; small soda blast gun; soda media; small grit walnut shell blast media; large grit walnut shell blast media; aluminum oxide blast media; and an air dryer device to remove the moisture from the compressor line so that the media doesn’t clog. This would give me all the options without running back to the store all day.

Here’s what the “average” section of parapet looks like – some brick with a little tar, but several that are totally covered with black crud. The idea was to make it look like a regular brick wall.

Average amount of tar to be removed

Average amount of tar to be removed

There’s also an old piece of copper flashing embedded in the brick. I originally thought that it should remain, but after I chipped away some of the thicker tar covering the edge of the copper, I found that it was not well sealed, and it had been “repaired” many years ago by NAILING it back to the brick, which essentially made holes in something meant to be waterproof.

Pulling on the copper didn’t work so well; there was old horsehair packing stuffed into the joint. (Not sure what the real name for that is…) So I needed a hook-like tool to remove that. In my stack of metal parts down in the shop, I took apart an old radiator wall-mount and extracted this makeshift tool, which worked pretty well:

Makeshift tool

Makeshift tool

Removes packing well

Removes packing well

So I got the copper flashing removed… but back to the blasting.

I assembled the sandblast pot inside, figuring it would be easier on the second floor rather than the roof. My first alarm should have been that the included pipe tape for the threaded connections was so thin I could see through it. I had to use ten times as I usually do to get a good seal.

Then the bolts that hold the handles to the tank were  twice as long as necessary and they poked into the side of the main tank; not a problem now, but years of use could start a rust spot there. And I could never make the handles look straight.

Inside the main tank, there was plastic debris, like little black shreds. Puzzling. And the two wheels were slightly different sizes.

I hauled everything up to the roof, hoisting it all with a rope through the roof hatch. Pretty difficult. The compressor would stay below; I had plenty of hose to run to the roof.

Starting with light abrasion, I hooked up the small soda blaster, and filled it with the soda media.

Boooo…  almost no effect at all. It spit bits of white soda at the wall and really just CLEANED the tar. Not aggressive enough.

Then for the big pot – I filled it with the larger grit walnut shell, pressurized it per instructions, and fired away. About 7 granules of shell flew out and then nothing. Hmmm… seemed like a jam. I killed the pressure and removed the tip. Sure enough, lot of shells right behind the tip.

Turned the pressure back on with the tip OFF and blasted the shells – they flew out in an enormous spray but with no force. This told me that they were locking up when the tip was on.

Tip back on, tested again. Same blockage. Repeat steps above. Two more times. Okay – that sucks.

Then I installed the deadman valve (it’s a special valve that automatically kills the blasting when you release your hand) because it had tips with larger holes. But it clogged too. I looked closely at all the tips and they all had a little rubber gasket behind them; it looked like the shells were jamming at the little rubber hole. I went back down to the shop and found an o-ring that that would seal but provide a larger opening.

But to no avail.

On to other stuff… Repeated EVERYTHING above using the smaller grit shells.

No go.

It was dark now – a whole day wasted.

The next day I thought I’d try installing the air dryer. (It was at a $50 part that I”d prefer to return if not needed). So I put it together (another set of instructions obviously not originating in English) and installed it between the compressor and the blaster.

I repeated everything from the day before. And everything still clogged. But now, I was starting to see little bits of plastic jamming the hole in the tip – the same black plastic bits I found when I was assembling the pot.

If I could only run the hose without the tip, it would have been fine. But I couldn’t; it wasn’t.

I checked the air dryer. Yep – it was working, I could see moisture in the vials. In fact it was working too much – the “blue” crystals had already turned to “pink” and according to the directions, when they turn pink you’re supposed to replace them. Sheesh. That was about 2 hours worth of air drying.

ON to my last hope: the aluminum oxide media. This was a fine black sand-like material, that flowed and poured very smoothly. But it was expensive – about $42 for two gallons. I poured it all into the pot, sealed it up and cranked up the air pressure.

And the aluminum oxide somewhat worked; it just flowed out too fast. I killed the air supply and checked all the valves with the directions – there was supposedly a “throttle” valve to control how much media was expelled from the pot. Except it didn’t seem to make a difference. With the throttle wide open, the alum oxide media blew out fast & furious, but it removed the tar well – except I could see it was WAYYYY too much media; it would be all gone in mere minutes. Then I closed the throttle half-way – but no difference. I even closed the throttle completely – and it still blew out like crazy.

I stopped and shut everything down. Reviewed all of the directions, make sure I had everything installed & connected properly. Check.

The media was more than half gone now. Started everything up again – no change.

I’m throwing in the towel. Thinking I should just use up the media and see what it would do, I fired the pot back up again and blasted what I could. The rest of the media was all gone within 2 minutes. But when it blew out, it worked well and was very aggressive. I calculated that if I wanted to use the aluminum oxide media with this sandblast pot, just the media required to clean my tall parapets would cost me about $2000.

Areas clean with sandblasting - 2+ days worth...

Areas cleaned with sandblasting – 2+ days worth…

Harbor Freight claims to have a good return policy; the guy in the store that helped me even said “If it doesn’t work out, just bring it back…” But when I looked at the fine print on the receipt, it said there was a 20% restocking fee on anything that was not considered resalable and that was up to the manager’s discretion. But that was better than holding on to this piece of junk.

I DID have a little trouble returning it – they had to call a manager over and I had to explain the details of my project and what the sales guy (“sales guy”? more like slacker stocker) told me about returning stuff; and I intended to return EVERYTHING I purchased. Since the aluminum oxide was all gone, they wouldn’t give me a refund on an empty 2-gallon container. Okay, fair enough, so the whole ordeal was only a $40 loss then.

Well, only $40… AND MY ENTIRE WEEKEND!

Looks like I’m going to have to find another solution to my tar removal problem.

3 Comments leave one →
  1. Susan permalink
    August 14, 2013 7:53 am

    Sorry you wasted so much time – but now you know to STAY AWAY from that place. Everything they sell is sub-standard, hence the “low prices”.


  1. Brick & Tar Removal | B. A. B.

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