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View Full Version : Sandblasting attachment for pressure washer any good?



DICKEYBIRD
03-28-2011, 04:10 PM
I bumped into a sandblasting attachment that hooks up to your pressure washer in the Northern Tools catalog. My pressure washer has a LOT more oomph than my air compressor. My sandblasting needs are few and far between on relatively small stuff so it looks like a pretty good idea to me.

Anybody used one?

Dan Dubeau
03-28-2011, 04:26 PM
Probably be good for getting graffiti off of concrete, but for anything with any Iron content i'd expect flash rust. Might be good for an old boat or skidoo trailer, getting repainted with rustoleum black, but for that old hotrod project id stick to the old fashioned way.

CCWKen
03-28-2011, 04:29 PM
To me, that sounds like accessory screen doors for a submarine--Perfectly useless. :rolleyes: It's hard enough trying to keep flash rust off newly blasted metal but throwing water on it while you're blasting is a guarantee for rust. I couldn't find it online, how does it attach or what's the product number?

DICKEYBIRD
03-28-2011, 04:32 PM
Here's a link:

http://www.northerntool.com/shop/tools/product_8520_8520

CCWKen
03-28-2011, 04:33 PM
Good point Dan. I didn't think of cleaning concrete, stone or masonry. For that, yes but not for metal. I guess we tend to limit our field of view to what we know. :o

CCWKen
03-28-2011, 05:14 PM
The price isn't bad but count on adding a box of those $27 tips if you do a lot of blasting. I go through a ceramic tip about every 8-12 hours of sandblasting. The hardened metal tips I used to get lasted about 4 hours. The carbide tips for my blaster are just too expensive no mater how long they last but I don't even see those lasting more than 20 hours.

radkins
03-28-2011, 05:16 PM
Flash rust is not a problem at all with the attachments when blasting metal, when using one to remove old paint or heavy rust the flash rusting that occurs is nothing compared to the old paint or heavy pitted rust! Just remove whatever is on the surface, let the metal dry and then wipe it down with Phosphoric acid (Ospho at Lowes or Home Depot or any number of other home supply stores). The flash rust will disappear INSTANTLY and the surface will be left with a rust resistant Phosphate coating that needs only to be brushed after drying to prep for paint. Flash rust is a non-issue!


BTW, Phosphoric acid is very mild and it is not even necessary to wear gloves but it does sting if you get it in a cut!

lbhsbz
03-28-2011, 06:17 PM
That sounds like a neat idea.....I've got a fence around my yard that's all rusty. Conventional sandblasting would make a mess(too much media), and by hand with a grinder would take me a month. I'm gonna research this...probably buy one and do a review

radkins
03-28-2011, 06:28 PM
Fair warning to anyone thinking of sandblasting auto body sheet metal with one of these, it is well known that sandblasting can ruin body parts and wet blasting will warp thin sheet metal just as quickly as dry blasting! There is a common misconception that wet blasting keeps the metal cool which will prevent warping BUT the problem is heat has absolutely nothing to do with it in the first place! The warpage is due to the peening effect on the metal and the common belief that the metal warps from heat generated by blasting is in error, the warpage is from the metal being displaced by the peening effect and not from heat so wet blasting does not prevent thin metal from being warped by sandblasting.

Arcane
03-28-2011, 06:37 PM
Flash rust isn't a problem if you're going to paint it with POR 15. :D

You might want to check the minimum operating volume and pressure that the water blasting equipment might need. The linked one says "up to 8 GPM and up to a max. of 3500 PSI" but I've seen ones here at Princess Auto where they do state a minimum requirement. Specs here. (http://www.princessauto.com/all-seasons/seasonal/pressure-washers/accessories/other/8067399-wet-sandblast-kit)

aboard_epsilon
03-28-2011, 07:07 PM
Whenever I'm cleaning some bare metal up ..

and I have to get a load of grease off it etc.

I always pour boiling water over it ..pour enough so the whole part gets hot right to the core ..

Then, it's so hot, that the water evaporates off it imediately..and it dries in seconds.

I do this after electrolysis method of rust removal too.

Maybe, the last few min's, can be spent pouring hot water over the item, after you've sandblasted it with this device, then it wont rust so much.

all the best.markj

radkins
03-28-2011, 07:18 PM
Flash rust isn't a problem if you're going to paint it with POR 15. :D


Flash rusting is not a problem period! Why would it be? Flash rust is so simple to deal with it is no problem at all, it really is just as simple as wiping it down with any of the very common Phosphoric acid solutions and the Flash rust really does disappear instantly, hell you can even remove it easily with Coca Cola! The Phosphate coating left from the wipe leaves an excellent surface for paint or primer and even if not painted it will be far more rust resistant than if the surface had been left untreated after dry blasting. Removing flash rust is not at all the same as heavy rust and there is no waiting for the solution to dissolve the rust, when it is wiped down with Ospho or similar the flash rust disappears INSTANTLY and completely.

Black_Moons
03-28-2011, 07:29 PM
BTW, Phosphoric acid is very mild and it is not even necessary to wear gloves but it does sting if you get it in a cut!

Uh. I think this HIGHLY depends on the consentration. 85% is not uncommon to find sold over the counter, And I highly suspect would be very corrosive to flesh. No idea what % is commonly used in rust remover formuals, But DEFINATELY wear gloves when dealing with phosphoric acid of unknown consentration. And I have no idea what % is 'safe' either. I don't think you wanna find out the hard way either. I have only ever used 3% without safty equipment, And I take MUCH care never to spill it or touch it, and wash up after use.

radkins
03-28-2011, 07:46 PM
Uh. I think this HIGHLY depends on the consentration. 85% is not uncommon to find sold over the counter, And I highly suspect would be very corrosive to flesh. No idea what % is commonly used in rust remover formuals, But DEFINATELY wear gloves when dealing with phosphoric acid of unknown consentration. And I have no idea what % is 'safe' either. I don't think you wanna find out the hard way either. I have only ever used 3% without safty equipment, And I take MUCH care never to spill it or touch it, and wash up after use.


You are definitely right about that and I should have been more clear about the products I am talking about. The one's at Lowes, Home Depot, Wally World, almost any auto parts store, etc are not going to be dangerous at all however. Basically any of these products sold for rust removal are quite harmless, Ospho, Navel Jelly, or any number of other brands commonly sold at home supply and hardware stores are not going to hurt anything. An industrial chemical of unknown concentration however could be dangerous but that is not the case with these brand name rust preparations I have mentioned nor is any higher concentrations necessary. Flash rusting really can be removed with little effort using these easily found products so I fail to the see the worry about wet blasting metal, I do it all the time and have exactly zero problems with rust. Flash rust most certainly will appear but will disappear as if by magic just as fast as the Phosphoric acid solution is wiped on so where is the problem?

Bill736
03-28-2011, 09:02 PM
I have not tried the pressure washer sandblasting attachment, so I can't judge the practicality. It occurs to me, however, that one advantage of such a method is to allow the use of silica sand without the dust usually generated. As we know, breathing that dust is quite unhealthy, and apparenty common respirators are not adequate to protect against fine slilca sand particles. There will still be some cleanup of sand involved, but probably won't involve the clouds of fine particles generated by air/sand blasting. The concept of water jet blasting with grit added is well established for cutting and cleaning materials, and I suspect that's where the idea for this accessory originated.

DICKEYBIRD
03-28-2011, 09:49 PM
I've got some spots out back that could use some water and sand. Maybe I can fit one into the household budget under "Lawn Maintenance Equipment"!:D

ps: As far as the rust goes, I figure a light, even coating of flash rust is part of a long-lasting paint job along with one of the many brush or spray-on rust converters out there.

radkins
03-29-2011, 07:00 AM
Dicky, those "converters" do not work as well as they claim but even if they did flash rust would be an extremely poor base for any of them, flash rust is a dusty type coating with very little adhesion compared to the ingrained heavier rust that those "converters" are meant for. A sandblasted surface with a Phosphate coating etched into it is a much better surface for painting and in fact was the procedure for prepping body panels for years before the newer paint products became available. When the standard for most body shops was Lacquer primer as a substrate for paint topcoats the bare metal was prepped with these acid products to remove any flash rusting and to provide and etched surface for the primer to adhere to.

Bill736
03-29-2011, 12:25 PM
This thread reminds me of something I learned on the Rust-Oleum web site.
Their " Rusty Metal" primer is only designed to prime rusty metal, and not clean metal. The fish oil in their primer is absorbed into the rust layer. If there's no rust, the fish oil stays at the surface and may interfere with the adhesion of topcoats. I find that a bit odd, since we often paint surfaces that have both rusty spots and clean spots. It may also depend on exactly what topcoat you use, but that subject was not covered in the brief Q&A section I read.

Silverback
03-30-2011, 02:26 PM
Flash rust is not a problem at all with the attachments when blasting metal, when using one to remove old paint or heavy rust the flash rusting that occurs is nothing compared to the old paint or heavy pitted rust! Just remove whatever is on the surface, let the metal dry and then wipe it down with Phosphoric acid (Ospho at Lowes or Home Depot or any number of other home supply stores). The flash rust will disappear INSTANTLY and the surface will be left with a rust resistant Phosphate coating that needs only to be brushed after drying to prep for paint. Flash rust is a non-issue!

Were do you live that you can get ospho at the home centers? I've never seen it anywhere locally even though they list it as having it at the Ace hardware stores (turns out they can order it, if you can find someone at the store that knows how to order something).

Rosco-P
03-30-2011, 03:06 PM
Were do you live that you can get ospho at the home centers? I've never seen it anywhere locally even though they list it as having it at the Ace hardware stores (turns out they can order it, if you can find someone at the store that knows how to order something).

Ospho Metal Prep used to be carried by Lowes, but not any more. Did you try Home Dee or a Service Star or Sentry hardware?

CCWKen
03-30-2011, 03:31 PM
LOL...
How is blasting something clean then making it rust and tripling your work by coating it with chemicals that needs to be brushed off before painting a "non-issue"? :rolleyes:

You have got to be union! :D

Thank goodness you're not working on my cars or equipment. :cool:

radkins
03-30-2011, 04:41 PM
LOL...
How is blasting something clean then making it rust and tripling your work by coating it with chemicals that needs to be brushed off before painting a "non-issue"? :rolleyes:

You have got to be union! :D

Thank goodness you're not working on my cars or equipment. :cool:



Because flash rust is in no way the same thing as "heavy" rust as far as removing it. You obviously do not have a clue but yet you will roll your eyes? Removing the flash rust takes almost no effort so how the hell is that going to "triple" your effort? What seems to be the problem here? :confused: How come so much is being made of something as easy to deal with as flash rusting? It is as simple as WIPING IT WITH A WET RAG! Simply wet a rag with the solution and wipe it over the areas with flash rust, you don't have to rub it, scrub it or brush it the rust simply disappears instantly when it comes in contact with the solution. You then not only have the rust removed but the surface is then treated with a rust resistant Phosphate coating that will help prevent further rust.


Silverback, Ospho is just one of the older brands that has been used fore this purpose for over 50 years and there are a bunch of differnt brands of the same solution, for example there is one called "The Right Stuff" sold by Advance auto parts. Almost any Home Supply store will have some brand of this solution, just look for it where they have cleaning and prep chemicals.

Another word of warning NEVER use Hydrochloric (Muriatic) or Sulfuric acid for this purpose in ANY amount or dilution!!!! These acids are a whole different animal and although they will quickly remove even heavy rust easily they will contaminate the surface and lead to major corrosion problems, just the opposite of what Phosphoric will do with the Phosphate coating. Neutralizing Hydrochloric or Sulfuric acid on a sandblasted surface is nearly impossible and is not as simple as soaking with a neutralizing solution in spite of what some might think.