With a normal dry-pickup siphon type sand blaster (as is sold cheaply at most auto stores) you have problems with media pick up, such as caking, and low suction.

A lot of the media is lost in uses where you don't have an enclosure to do it in. It gets scattered.

Also - if oil gets into the sand or other media it will cake tightly.

My thought was to use a five gallon bucket with a gallon of sand or other media, two or three gallons of water, and possibly some kind of soap to clean grease and oil out of the pores of the metal as the abrasive was applied. Common dish washing liquid comes to mind...

It seems to me that doing this will result in a much smoother less pitted surface - sort of like the difference between dry sand paper and using wet sand paper.

Adding lemon juice to the mix might also convert some of the material being worked on at the same time as corrosion is being removed. I have used lemon juice to clean carbon steel knives - the acid in it does the job.

The water and soap might also loosen stubborn deposits.

NONE of the above pose a chemical hazard, and the dust inherent in dry blasting is not present to any large degree.

For a containment one could almost just use an old bathtub with a five gallon bucket under the drain...

Has anyone heard of anything like this?

"WET Sand Blasting"

 

It sounds more like pressure washing with grit. What would you use to squirt this stuff?

 

yeah that's what I'm worried about. the wetness might give you a problem. Sure the water wouldn't give you a clumping problem?

 

They do make pressure washers with a "sand blast" attachment.

 

Yes, a friend has one of those attachments for his pressure washer. It did a nice job of cleaning the gunk and rust off a front axle. No dust, but sandy water went _everywhere_.
Worth considering if you already have a pressure washer.

 

Auto Zone has a cheap basic sand blaster that they sell for about ten bucks.

It looks like a big air nozzle with a long rubber hose hanging off of it.

They are in the air tool section.

 

I've heard good things about using the grit in the pressure washer, but it does seem like a rust hazard. I don't know if a regular sandblaster would have enough pressure to do the job. I know the air powered pressue washers always seemed a little underpowered.

 

Those little syphon feed sand blasters don't have enough power for much more than cleaning sparkplugs...the pressure washer/sand feed is called a water blaster,and is used often for graffiti removal,they actually work pretty nice.And you can inject soap or degreaser.But I like your idea of the lemon juice on the metal.you can also get some metal "washes" from an automotive paint supply that may work in the same application,and they neutralize the metal surface for paint.

 

Experience today with just plain sand out of the basic blaster:

It strips paint real well, but leaves a highly etched surface even using plain old "Play Sand" as is supplied at many home and garden stores for sandboxes. Deep rust seems to be a problem for it.

The way to smooth out the roughly etched surface fastest is to mount a small wire wheel in a die grinder, and go over it with that. It will smooth out the surface to just about a polished state.

Also - the siphon should not be stuck too deep into your sand bucket (I use a five gallon plastic bucket). When/If it clogs, cover the nozzle of the blaster with a finger to block the air flow and hit the trigger. This will blow any overlarge objects (such as stones) out of the siphon hose and clear the pickup tube, the blaster will then work normally.

I didn't think the unit would work very well, but sand is light enough to be picked up with the airflow from a standard compressor for the home shop.

Over all I was very pleased - it saved me spending all afternoon on just one MC fender, and I actually got the fuel tank done as well.

 

REALLY,I'm impressed.

 

Hey Grey... couldn't tell if your above test report was with or without the water. Sounds like it might work conceptually but wasn't sure if there would be enough suction to pull the weight of water and sand up the feed tube.

 

I have been using it with about ten gallons of water and enough sand to cover the bottom of a fifty five gallon plastic barrel plus some dish soap to clean out oil and grease most of today.

I set a length of four by four under one edge of the barrel to tip it to one side, and have been trying different things to get the flow to be constant without clogging the pickup tube - I think less sand in the barrel might be helpful. I'll figure it out...

Some kind of strainer, even an old oil pump strainer might be useful.

I found that the sand does not scatter nearly as much as before, and the surface of the work is not nearly as deeply etched. Also - the longer a rusted piece is kept wet the easier it is to blast deep rust. The soap and water help to loosen it.

Going back and forth between the blaster and a die-grinder mounted wire wheel I have cleaned off some serious deep rust from an old lawn tractor fender that I wasn't sure if I could get down to metal on at all!

The earlier try was with just plain dry sand, and this attempt today was mind blowing by comparison.

1) Better abrasive control. Most of it stayed in the barrel instead of drifting.
2) It degreases as it blasts.
3) Smoother surface after blasting - "etching" is reduced at least 30%
4) Lifting the pickup tube out of the grit allows washing off of most of the sand.

Downsides:

Reverse blowing the pickup tube may blow sand in your eyes if you are not careful. A clogged tube may blow off of the gun, or the metal end may blow off the end of the pickup tube. Wear safety goggles or glasses, and look away when clearing the pickup tube.

HOWEVER - it will pickup the sand. Yes, it does have a tendency to clog up, I am still working on that.

The pickup tube works a lot better if it is no longer than it absolutely has to be. I trimmed off about two thirds of the length of mine, and it improved it a lot.

One thought: If I had some way to agitate the water and sand in the bottom of the barrel (sort of swirl it constantly) the sand might mix with the water (cloud it) and I could pick it up without the siphon having to be stuck right down in the media. I'm not going to mess with that right now though.

DEFINITE OBSERVATION:
The unit will strip off old paint very satisfactorily, although it has a tough time with deep rust. Use of water as a solvent and lubricative agent greatly reduces pitting and etching, while enhancing the removal of unwanted materials. The further addition of a detergent or soap also removes oily substances wonderfully.

Overall, I think my experiences today were an improvement.

NOTE: You may have to lube the air control valve with Mystery oil if it sticks open. Remove it with a suitable wrench, lubricate the valve assembly and work it in and out to the open and closed positions while turning it. Under no circumstances use pliers to pull the valve shut from a stuck open position - it is made of brass and can be scarred easily.

Be suitably cautious of the "O" rings on the valve so as not to damage or lose them in removing and reinstalling the valve in the gun.

 

I am posting this seperately because it is a seperate idea.

For degreasing engine compartments (engine removed) you can use one of these with a bucket of hot water and dish soap to spray the engine compartment and firewall.

It is less expensive by far than a pressure washer, and overspray is not at so high a pressure that it can damage rubber parts.

Dish soap and water will not attack paint either - as might be a problem with some engine cleaners or oven spray.

 

I found that if you sift the sand through a window screen, you almost never get a clog.

 

Use dry sand only with the proper breathing apparatus, it is very dangerous.