Sandblasting material

[Thetireddad]

Hi guys,
I am going to be sandblasting the undercarriage on my bus and wondered what grit/ material everyone used? I was planning on getting a portable sandblaster from harbor freight and going to town.
Thanks

 

[o1marc]

I do a lot of sandblasting for my business. For all the small stuff I use a fine grit coal slag (Black Diamond). For lager things my friend does them in his booth at his blast business and uses a 000 sand.
Here's some info that will help you decide which grit to use.

https://www.blackdiamondabrasives.com/products/black-diamond-coal-slag/

 

[ewo1]

Hi guys,
I am going to be sandblasting the undercarriage on my bus and wondered what grit/ material everyone used? I was planning on getting a portable sandblaster from harbor freight and going to town.
Thanks

Greetings Tired Dad,

I do lots of sandblasting here in South Florida so I can speak from first hand experience.

First I would like to agree with o1Marc, Coal slag aka black beauty is great stuff but there their are other options that I would like to share with you.

I personally do not use COAL SLAG outside of a blast cabinet because of the dust cloud it leaves but it is great stuff when used in a blast cabinet or with a wet blasting system such as mine. I have a Farrow system in my shop to blast wet.

Any dry blasting used will leave some sort of dust cloud of some sort. This is important not just because of the cleanup issues but the last thing you want to do is breathe in any of the blasting dust materials while you are doing this type of work.


WARNING: NEVER OPEN AIR DRY BLAST WITH SAND !!!


Dry blasting with sand creates microscopic fine dust containing free silica which WILL cause Silicosis in the lungs... this is only curable by replacing the lungs so please do not do dry blast with Sand!!

Wet blasting with sand is acceptable but only if you have the right equipment!

Ok...
If you are going to be under the bus and blasting very small problem spots a dry Harbor freight pot will work just fine but you WILL need to use some sort of personal protection equipment not only for your lungs but also for your eyes and ears...yes ears! Any and all blast material will find its way into the ear canals.

In order to avoid this I personally use a Nova 3 air feed blast helmet along with a disposable tyvec paper suit.

For the one time backyard user I would suggest you look at using a pressure washer with a sandblasting tip attached to it...works wonders !!

Here is a northern tool video on the pressure washer sandblast attachment.

You will get soaking wet while doing this but there are advantages that make it all worthwhile.

You wont be breathing in any dust because it is all wet and will immediately fall to the ground!

You can use screened blasting sand, not play sand. Play sand from the big box stores is full of larger particles that will clog up the tip!
If using sand (wet), I would recommend a 20/30 grit for the underside of the bus.

But, I would personally recommend using crushed glass instead. It contains practically no free silica, it is very reasonably priced and the crushed glass by itself is safe to dispose of in the trash. Rust under the bus is typically not a hazardous waste so you would be safe in dumping that in the trash to.
If you use crushed glass use either a fine or medium grit.

After you finish blasting you will want to treat the clean raw steel with some sort of rust treatment. My number one choice is OSPHO.

Raw clean steel that has been recently blasted wet or dry will begin to flash rust almost immediately. You do not want to blast then paint without treating as rust WILL begin to form under the paint and you will have a paint failure event sooner or later. OSPHO is cheap so remember an ounce of prevention is worth a pound of cure.

Once you clean, treat and are ready for paint please be sure to use an epoxy primer to seal in the blasted work area. Regular 2k primer will bleed, will allow moisture to penetrate thus creating the opportunity for more rust growth.

I hope you find this info helpful and again please, PLEASE, DO NOT DRY BLAST WITH SAND !!!

Oh yeah I almost forgot, no matter what blasting media you use, be prepared to use quite a bit. On a 30 foot boat, while taking off the antifoul bottom paint I will typically use about 600-700 lbs of sand. ( remember I blast wet not dry!)

 

[Sleddgracer]

Greetings Tired Dad,

I do lots of sandblasting here in South Florida so I can speak from first hand experience.

First I would like to agree with o1Marc, Coal slag aka black beauty is great stuff but there their are other options that I would like to share with you.

I personally do not use COAL SLAG outside of a blast cabinet because of the dust cloud it leaves but it is great stuff when used in a blast cabinet or with a wet blasting system such as mine. I have a Farrow system in my shop to blast wet.

Any dry blasting used will leave some sort of dust cloud of some sort. This is important not just because of the cleanup issues but the last thing you want to do is breathe in any of the blasting dust materials while you are doing this type of work.


WARNING: NEVER OPEN AIR DRY BLAST WITH SAND !!!


Dry blasting with sand creates microscopic fine dust containing free silica which WILL cause Silicosis in the lungs... this is only curable by replacing the lungs so please do not do dry blast with Sand!!

Wet blasting with sand is acceptable but only if you have the right equipment!

Ok...
If you are going to be under the bus and blasting very small problem spots a dry Harbor freight pot will work just fine but you WILL need to use some sort of personal protection equipment not only for your lungs but also for your eyes and ears...yes ears! Any and all blast material will find its way into the ear canals.

In order to avoid this I personally use a Nova 3 air feed blast helmet along with a disposable tyvec paper suit.

For the one time backyard user I would suggest you look at using a pressure washer with a sandblasting tip attached to it...works wonders !!

Here is a northern tool video on the pressure washer sandblast attachment.

You will get soaking wet while doing this but there are advantages that make it all worthwhile.

You wont be breathing in any dust because it is all wet and will immediately fall to the ground!

You can use screened blasting sand, not play sand. Play sand from the big box stores is full of larger particles that will clog up the tip!
If using sand (wet), I would recommend a 20/30 grit for the underside of the bus.

But, I would personally recommend using crushed glass instead. It contains practically no free silica, it is very reasonably priced and the crushed glass by itself is safe to dispose of in the trash. Rust under the bus is typically not a hazardous waste so you would be safe in dumping that in the trash to.
If you use crushed glass use either a fine or medium grit.

After you finish blasting you will want to treat the clean raw steel with some sort of rust treatment. My number one choice is OSPHO.

Raw clean steel that has been recently blasted wet or dry will begin to flash rust almost immediately. You do not want to blast then paint without treating as rust WILL begin to form under the paint and you will have a paint failure event sooner or later. OSPHO is cheap so remember an ounce of prevention is worth a pound of cure.

Once you clean, treat and are ready for paint please be sure to use an epoxy primer to seal in the blasted work area. Regular 2k primer will bleed, will allow moisture to penetrate thus creating the opportunity for more rust growth.

I hope you find this info helpful and again please, PLEASE, DO NOT DRY BLAST WITH SAND !!!

Oh yeah I almost forgot, no matter what blasting media you use, be prepared to use quite a bit. On a 30 foot boat, while taking off the antifoul bottom paint I will typically use about 600-700 lbs of sand. ( remember I blast wet not dry!)

I've blasted both wet and dry - wet definitely does have some advantages - with wet, you have no dust - protective clothing can be as little as long sleeves, gloves and a face shield ( rain clothes are a definite help ) - the disadvantages include the amount of sand needed and on larger jobs, what to do with the run off, and as mentioned above, flash rusting when blasting steel - dry blast reduces costs for sand as good sand can be used 2 or 3 times, depending on the surface being blasted - hard surfaces like steel dulls the sand quicker and 2 uses is likely all you can expect - concrete, in most cases allows 3 uses of the sand because of the more resilient surface - run the sand through a suitably sized screen to rid it of unwanted material - dry sanding requires an air fed sandblasting helmet and a charcoal filter for the air supply ( you don't want to be breathing any oil that the compressor might be mixing with the air it sends through the lines ) - the negatives with dry blasting is mostly the dust it creates - it does go everywhere - neighbors will complain about it if they are nearby - ( we were blasting 30 years of paint off a city swimming pool one time - hour after hour after hour, the hypnotic sight of the 1/2 inch wide line made by blasting, and the hissing sound of air in his helmet caused my guy doing the blasting to fall asleep on his feet - lol his arm and hand continued moving, his body was still making it's side to side rocking, but he wasn't advancing - it took minutes to realise something was wrong - shutting off the sand woke him up with a start - lol )

 

[tugboater-SKO]

I do a lot of sandblasting for my business. For all the small stuff I use a fine grit coal slag (Black Diamond). For lager things my friend does them in his booth at his blast business and uses a 000 sand.
Here's some info that will help you decide which grit to use.

https://www.blackdiamondabrasives.com/products/black-diamond-coal-slag/

Funny this thread surfaced just as I need to do a little research and make a purchase for a project at work. Have you ever used crushed glass as media?

 

[o1marc]

Funny this thread surfaced just as I need to do a little research and make a purchase for a project at work. Have you ever used crushed glass as media?

Not very often, it costs more than the product I need to do the job I want. There are also glass beads that leave a different finish. So the media can also depend on what finish you are wanting. Glass beads are quite a bit more expensive than crushed glass. Grit size is critical as too big will either clog the nozzle or be too big for the blast pressure to even pick up and move through the hose on a low pressure situation.

 

[tugboater-SKO]

I do a lot of sandblasting for my business. For all the small stuff I use a fine grit coal slag (Black Diamond). For lager things my friend does them in his booth at his blast business and uses a 000 sand.
Here's some info that will help you decide which grit to use.

https://www.blackdiamondabrasives.com/products/black-diamond-coal-slag/

Funny this thread surfaced just as I need to do a little research and make a purchase for a project at work. Have you ever used crushed glass as media? I've got a project coming up that'll require quite a bit of this type of work and I've been pointed toward crushed glass.

 

[tugboater-SKO]

Not very often, it costs more than the product I need to do the job I want. There are also glass beads that leave a different finish. So the media can also depend on what finish you are wanting. Glass beads are quite a bit more expensive than crushed glass. Grit size is critical as too big will either clog the nozzle or be too big for the blast pressure to even pick up and move through the hose on a low pressure situation.

Thanks man..Sorry for the double post...need more coffee

 

[family wagon]

I've done a medium amount of backyard media blasting with the 100 pound Harbor Freight pot. The hood that comes with that thing looks like it came from the costume aisle at the dollar store; I bought a much nicer one from Eastwood. I don't recall what media I'm using since it's been so long since I bought the stuff. Green diamond slag something-or-other, I think.



Tell us more about respiratory protection. When I blast I wear a respirator with P100 filters. Obviously the filters plug up fairly quickly, but would you say this level of protection is much different or worse to the supplied-air type a professional would use?

 

[Sleddgracer]

I've done a medium amount of backyard media blasting with the 100 pound Harbor Freight pot. The hood that comes with that thing looks like it came from the costume aisle at the dollar store; I bought a much nicer one from Eastwood. I don't recall what media I'm using since it's been so long since I bought the stuff. Green diamond slag something-or-other, I think.



Tell us more about respiratory protection. When I blast I wear a respirator with P100 filters. Obviously the filters plug up fairly quickly, but would you say this level of protection is much different or worse to the supplied-air type a professional would use?

workman's compensation specifies air fed helmets and charcoal filters - when I first started sandblasting, our union had to fight to get little charcoal filters that hooked on our belts - guys were coughing up oil and blood before we got the filters - now the requirements have gone from those small filters to large stand alone filters that might put you in mind of a fire hydrant - more recently the rules banned silica sand because of the silica dust - kind of miss it because the silica sand is much sharper than slag and the job went quicker - my strong advise is to rent an air supplied helmet with a proper filter - that dust is nothing to fool around with and can do permanent damage to lungs - I have COPD now, possibly partly caused by sandblasting with the inadequate equipment supplied on the job, working with no protective equipment while using dangerous paints that had no warning labels on them, handling powdered asbestos with no mask or protection of any kind to fix an old furnace in the first house we bought - still finding out via the news that the 1000's and 1000's of pounds of texture I sprayed ( without the use of even a dusk mask on ceilings had asbestos in it, that the 'harmless' latex that we sprayed mask-less outdoors had mercury in it thinking that it had no lead in it - the fact that I've smoked a pack-a-day for 62 years likely doesn't help either - lol - I've already passed my 'best before date' and still pushing - can't imagine what a PITA I would have been had I treated my body and lungs with respect - lol

 

[Thetireddad]

That was invaluable. Does the tip attach fairly easily to most pressure washers?
Do you have any recommendations on where to get the sand? And finally what type/ brands of paint do you use? Is it applied with a brush or sprayer? It looks like I’ll be doing the work in 1 week phases
1. Power wash and see the lay of the land
2. Wet sand blasting (thanks for steering me in right direction).
3.using the ospho (how much for a 40 ft bus)
4.Then painting

Is it safe to say essentially ospho and paint everything that is metal? I’m very new.
Thanks you SO much for the insight

 

[Thetireddad]

Ewo,
Question about the wet pressure washing.
So I will need:
The pressure washer
The northern tool kit
Filtered sand
Where does the sand draw from so I need an actual sandblaster as well?

On a different note. I was planning on pressure washing underneath before I did anything. Do you feel that’s an unnecessary step? Should I just do the wet sand blasting and save the time?

 

[Sleddgracer]

Ewo,
Question about the wet pressure washing.
So I will need:
The pressure washer
The northern tool kit
Filtered sand
Where does the sand draw from so I need an actual sandblaster as well?

On a different note. I was planning on pressure washing underneath before I did anything. Do you feel that’s an unnecessary step? Should I just do the wet sand blasting and save the time?

you don't need to pressure wash first - you should be able to purchase the sand at the tool rental where you rent the pressure washer and the attachment that allows the sand to become part of the water stream - get the operator of the tool rental to go over the operation of the equipment with you - once you know how to set everything up, a half hour of practice will have you blasting like a pro

 

[o1marc]

Ewo,
Question about the wet pressure washing.
So I will need:
The pressure washer
The northern tool kit
Filtered sand
Where does the sand draw from so I need an actual sandblaster as well?

On a different note. I was planning on pressure washing underneath before I did anything. Do you feel that’s an unnecessary step? Should I just do the wet sand blasting and save the time?

The wet blaster will use vacuum to suck sand up it's own tube to mix with the water as it comes out. As long as the tube is in the media it will suck it up.

 

[Native-SKO]

Has anyone used crushed walnut shells as a blasting media?


Pros/cons?

 

[ewo1]

Ewo,
Question about the wet pressure washing.
So I will need:
The pressure washer
The northern tool kit
Filtered sand
Where does the sand draw from so I need an actual sandblaster as well?

On a different note. I was planning on pressure washing underneath before I did anything. Do you feel that’s an unnecessary step? Should I just do the wet sand blasting and save the time?

Tireddad,

The Northern tool sandblast tip basically screws onto the pressure washer wand, easy peasy….

As far as where to get the sand/media.

If you do not have a local sandblast media supply company where you are at then try going to where they might sell tile, paver bricks.

Many times these supply chains will have masons sand or paver sand that is filtered.
Do not worry so much on grit size but do try to stay in between fine and coarse, no coarse media as it might plug up the tip of the blast adapter.

As far as how much should you buy ??? 200 lbs at a bare bones minimum. Any left over you can use for other blast projects.

Please let us know how it all works out for you at the end.

Also, please edit your user profile to show where you are from, Thanks and good luck.

 

[ewo1]

Has anyone used crushed walnut shells as a blasting media?


Pros/cons?

Too much of an open ended question my friend.
Each and every blast media type will give you different results based on the methods, equipment and techniques the operator utilizes.

Walnut shells is great for cleaning wood surfaces, removing paint from surfaces where you do not want much, if any, of a profile.

Some examples of this wood be log cabin, cleaning or removing of paint and stains of wood, doors or removing paint from say, a corvette or other sensitive exotics.
Antique furniture restoration, aluminum or non ferrous metals.

Another great place to utilize crushed walnut shells is for the removal of anti fouling paint from a boat bottom.

Used outside of a blast cabinet you cannot reclaim and reuse due to contamination of the media by the surface material you just blasted off.

Used within a blast cabinet you can reclaim and reuse if you utilize a cyclone type of dust collector.

Cons for me, media is quite pricey, upto $40-$50 a bag for a 50lb bag here in Miami.

I get the same results using a 50/140 (#7) grit sand when I blast wet. The cost of sand is only $6 for a 50 lb bag.

also you cannot blast crushed walnut with a wet slurry blaster such as mine or even the DB (green) machines that are heavily advertised on tv car shows.

You can blast it wet if you use a water ring on a dry setup but you cannot reclaim and recycle cause once it gets wet it is useless, becomes soggy just like a spitball!

For doing general homeowner style blast work, crushed glass/sand and a pressure washer will give you adequate results without breaking the bank.

Once you get into the special medias you will need to upgrade equipment and costs will go up with that too..


Here's a link that can explain things much better than I.

https://compomat.com/walnut-shell-b...hk45gW3RSlIjmDix3cCp1uADS0D7pYkAaAkmSEALw_wcB

 

[Sleddgracer]

Has anyone used crushed walnut shells as a blasting media?


Pros/cons?

as others have explained, walnut shells are not suitable for blasting rusty steel - they are more for gentle cleaning softer surfaces - ( art restoration experts go so far as to blast with talcum powder to clean up valuable paintings and antiques )

 

[Native-SKO]

Too much of an open ended question my friend.
Here's a link that can explain things much better than I.

https://compomat.com/walnut-shell-blast-media/?gclid=Cj0KCQjwt_nmBRD0ARIsAJYs6o28ryo.mk06Tujrxap7Dv-GZYhk45gW3RSlIjmDix3cCp1uADS0D7pYkAaAkmSEALw_wcB

Thank you very much for your detailed reply!


... and thank you for the link!

 

[Native-SKO]

as others have explained, walnut shells are not suitable for blasting rusty steel - they are more for gentle cleaning softer surfaces - ( art restoration experts go so far as to blast with talcum powder to clean up valuable paintings and antiques )

That explains a lot. My father is restoring a 1967 Datsun roadster. He brought the body into a blasting shop and they used walnet shells. Now I know it was because the metal was too thin to handle anything more abrasive.