Need Info On Soda Blast Media For Air Abrasion

[Fossildude19]

Hello all,

I have a few questions as I am about to begin my foray into air abrasive preparation with a cheap setup air eraser.

Total noob to this and was wondering:

A:) Where do you get the media from - any suggestions on good reliable suppliers?

B:) What kind of sodium bicarbonate am I looking for - fine, coarse, medium? 50 microns? 100? 150?

Any answers/suggestions appreciated.

Thank you in advance.

Regards,

[sharklover]

Hello

In Holland you have supply shops for farmers.

I bought me a bag of 25 kg for 14 euro .

Maybe you have in germany also sutch a shops.

I use it for me cretaceous fossils ,and it give a great result.

greetings

[TqB]

Hi Tim,

I'm fairly new to air abrading myself but was warned that, although it works well, sodium bicarbonate can seriously clog things if it gets at all damp.

I've mainly been using calcium carbonate from a specialist supplier in the UK, it's quite gentle and reasonably fast depending what you're using it on (mostly calcite fossils in calcareous shale in my case).

[Fossildude19]

@ Sharklover,

Thanks for your comments. I appreciate them.

@ TqB - Thanks for the info. I was told that most fossils from my area here in CT. (USA) are generally prepared with the Sodium Bicarbonate, as it will remove shale (sometimes extremely hard) and not damage the underlying fossils.

Regards,

[TqB]

Good luck, Tim, it'd be nice to see how you get on - a lot of my stuff's Lower Jurassic too.

[Uncle Siphuncle]

I operate at extreme bottom end $$$ so I don't even splurge for name brand Arm and Hammer....I just hit the echinoids with generic baking soda at about 125 PSI and am happy with the results. Sometimes the grocery store cashier will look at my 5 big boxes of soda and start asking questions to which I'll simply reply, "I had a craving" - end of unwanted conversation. Anyway most of these finds come from soft Cretaceous marine marls. Needless to say I've not had to take media size into account too much.

I've found a cheaper alternative than sieves for recovering media - I put a cheap, fine mesh frying pan splatter screen over the top of a 5 gallon bucket then tap/gently shake the screen to move the soda through, then discard the residual contaminants and repeat the process a cup at a time. Works pretty well but I've noticed that only virgin grocery store variety baking soda moves freely through small orifices such as .030 inch. .060 will move virgin or recovered media freely so that's what I use for 95+% of my gross blasting work. Not sure if the type of work I'm doing is similar or not to your application, so mileage may vary....

[Fossildude19]

I operate at extreme bottom end $$$ so I don't even splurge for name brand Arm and Hammer....I just hit the echinoids with generic baking soda at about 125 PSI and am happy with the results. Sometimes the grocery store cashier will look at my 5 big boxes of soda and start asking questions to which I'll simply reply, "I had a craving" - end of unwanted conversation. Anyway most of these finds come from soft Cretaceous marine marls. Needless to say I've not had to take media size into account too much.

I've found a cheaper alternative than sieves for recovering media - I put a cheap, fine mesh frying pan splatter screen over the top of a 5 gallon bucket then tap/gently shake the screen to move the soda through, then discard the residual contaminants and repeat the process a cup at a time. Works pretty well but I've noticed that only virgin grocery store variety baking soda moves freely through small orifices such as .030 inch. .060 will move virgin or recovered media freely so that's what I use for 95+% of my gross blasting work. Not sure if the type of work I'm doing is similar or not to your application, so mileage may vary....

Too funny!

Thank you , Dan. I will give it a go, and see what happens. And thanks for the splatter screen tip - will try that as well.

Regards,

[crinus]

I have used baking soda (the Arm and Hammer variety). You can dry it by spreading it on a cookie sheet and putting it in the oven for a bit to get rid of water. I also sieve it mainly to breakdown the clumped particles. That should work just fine in an air eraser.

crinus

[Fossildude19]

I have used baking soda (the Arm and Hammer variety). You can dry it by spreading it on a cookie sheet and putting it in the oven for a bit to get rid of water. I also sieve it mainly to breakdown the clumped particles. That should work just fine in an air eraser.

crinus

Crinus, thanks for the info.

I will give that a try.

Has anyone used a filter\moisture trap between the compressor and the air eraser to keep moisture to a minimum?

Regards,

[crinus]

Crinus, thanks for the info.

I will give that a try.

Has anyone used a filter\moisture trap between the compressor and the air eraser to keep moisture to a minimum?

Regards,

I have a mositure trap installed on my line. It is always in use. It is there to catch the water that will collect in your compressor. There have been many times that I have seen the trap full of water

crinus

[Fossildude19]

I have a mositure trap installed on my line. It is always in use. It is there to catch the water that will collect in your compressor. There have been many times that I have seen the trap full of water

crinus

Thank you, ... again, Crinus! Great info.

That nails it. I'll get the moisture trap in place before I start.

Regards,

[pleecan]

Hi Tim:

I use baking soda also, I bake the baking soda in an oven to dry out the moisture, then put it through a mini food processor to chop up and lumps.... I also use filters to take out the moisture in the compressed air.... good luck!

Peter

[Fossildude19]

Hi Tim:

I use baking soda also, I bake the baking soda in an oven to dry out the moisture, then put it through a mini food processor to chop up and lumps.... I also use filters to take out the moisture in the compressed air.... good luck!

Peter

Thanks for the confirmation, Peter.

Regards,

[Uncle Siphuncle]

when it is humid i push my compressor in the laundry room and run a hose to the garage. that way my home a/c pulls out the water before the air even enters the compressor...no clumping experienced in this setup mode.

[Uncle Siphuncle]

if you use a shop vac as a dust trap inspect/replace your filter before it leaks abrasive and burns up the motor

Edited May 12, 2011 by danwoehr

[Fossildude19]

if you use a shop vac as a dust trap inspect/replace your filter before it leaks abrasive and burns up the motor

Thanks for the additional info.

I'm pretty sure that the wife isn't gonna allow me to do this in the house.

Maybe I can spring for an A/C unit for the FS - when working with the fossils,... I'm banished to the Fossil Shed.

I'm actually going to be using an old hand held dirt devil vac to remove dust - with a brand new hepa filter installed!

I'll remember to check ift frequently, though!

Thanks again.

Regards,

[Ramo]

Tim,

I too use just palin old baking soda. At Walmart, you can get 5lb re-sealable plastic bags of it. I just keep it sealed, and don't get too many lumps. It works great on chalk, but I'm curious to see how it works on those hard rocks you have out there. Those are A LOT harder than chalk.

Ramo

PS don't forget to take some before and after photos so we can see how it goes.

[jpc]

FD19-

I also use bicarb. I get mne from the local abrasives store... (one of the few advantages of living in an oil town... yes we have abrasives stores). Who knows, maybe you have one nearby in CT, or in TX, Dan. Its pretty cheap in 50 lb bags. I sieve mine in an expensive soil seive No. 40, (I think)... cjeck ebay. As for air driers... yes yes yes. I live in very dry Wyoming and I have three air driers before you get to the air abrasive machine. In CT, where it is much more humid, you will need at least one and keep an eye on it. If one of them is a silica gel filter, you can reuse the silica gel by toasting it (or nuking it) for a short time when it turns pink.

As for the size, I am experimenting with different sizes, but it will depend on the size of your air abrasive set-up.

Edited May 12, 2011 by jpc

[Fossildude19]

Tim,

I too use just palin old baking soda. At Walmart, you can get 5lb re-sealable plastic bags of it. I just keep it sealed, and don't get too many lumps. It works great on chalk, but I'm curious to see how it works on those hard rocks you have out there. Those are A LOT harder than chalk.

Ramo

PS don't forget to take some before and after photos so we can see how it goes.

Thanks Ramo! I will be sure to take pics. I have my doubts too, this shale is so hard,... but this is what I've been told.

Regards,

[Fossildude19]

FD19-

I also use bicarb. I get mne from the local abrasives store... (one of the few advantages of living in an oil town... yes we have abrasives stores). Who knows, maybe you have one nearby in CT, or in TX, Dan. Its pretty cheap in 50 lb bags. I sieve mine in an expensive soil seive No. 40, (I think)... cjeck ebay. As for air driers... yes yes yes. I live in very dry Wyoming and I have three air driers before you get to the air abrasive machine. In CT, where it is much more humid, you will need at least one and keep an eye on it. If one of them is a silica gel filter, you can reuse the silica gel by toasting it (or nuking it) for a short time when it turns pink.

As for the size, I am experimenting with different sizes, but it will depend on the size of your air abrasive set-up.

Thank You, JPC.

I am gonna try to get a moisture trap with the silica. Thanks for the reuse tip!

Regards,

[siteseer]

For some fossils you cannot use aluminum oxide because it will rip into the surface before you can back away. You have to control the humidity of your lab to some extent.

One of my friends just uses Arm and Hammer. I will have to ask him why he doesn't use a generic brand because he goes through it quick and would save money switching over.

Hi Tim,

I'm fairly new to air abrading myself but was warned that, although it works well, sodium bicarbonate can seriously clog things if it gets at all damp.

I've mainly been using calcium carbonate from a specialist supplier in the UK, it's quite gentle and reasonably fast depending what you're using it on (mostly calcite fossils in calcareous shale in my case).

[Nandomas]

Just to stay hanged to this very interesting topic. I have a lot to learn from you, guys.

Nando

[Malcolmt]

Crinus, thanks for the info.

I will give that a try.

Has anyone used a filter\moisture trap between the compressor and the air eraser to keep moisture to a minimum?

Regards,

I am using a $24 filter/moisture trap that I got at Home Depot. Since I put it on I have not had a real problem with clogging. I tend to re-use the media by filtering through a sieve. I have not tried the oven trick as I really have not had a big problem with clogging. I run at 20 to 30 pounds. I find that the sodium bicarbonate is gentler the second time round (normally baking soda is has very sharp crystal edges theat get rounded when you use it.)

[Malcolmt]

For some fossils you cannot use aluminum oxide because it will rip into the surface before you can back away. You have to control the humidity of your lab to some extent.

One of my friends just uses Arm and Hammer. I will have to ask him why he doesn't use a generic brand because he goes through it quick and would save money switching over.

Calcium carbonate is just a little bit harder than sodium bicarbonate but way below auminum oxide or silicon dioxide. I would not use silicon dioxide as it is very nasty stuff if you breathe it in. BAking soda and calcium cabonate although I would not recommend intentionally breathing the dust seem to me to be a heck of a lot safer.

[Fossildude19]

Thanks Malcomt for the info - very helpful.

Regards,