Sand or Coal Slag for Media Blasting

Sand or Coal Slag for Media Blasting

One of Cleaned by Pete's media blasting set-ups, with our 16 hp motor and AR nickle plated pump putting our 4000 psi @ 4 gpm pressure washer built just for media blasting. This is the one you'll see us use if we're using coal slag or sand for blasting.

We have talked about soda for water blasting and how it works, sand and coal slag do somewhat the same thing but in a different way. First thing to remember is soda is a non-abrasive substance which means it will not harm the under lying surface. On the other hand sand and coal slag is very abrasive and can harm the surface under what is being removed. Sand and coal slag (which for time I will refer to as just "slag" for the rest of the blog) come in different grades and the higher the grade the larger the partial the more aggressive it is. If your machine can move and draw the larger particles it will work fine in the water stream.

Things to remember are too much draw of media, the less aggressive it will be. If you are trying to move to much media when it hits the water stream it will slow down and will have less impact on what you are removing. You can trow a small stone with more force than you can trow a large rock with more force. It take some adjustment to get a good stream of media flowing at the right speed or draw, but once you do things will go quite fast.

I will say this here having a good screened source for sand or slag will save you time. You make money by the hour or job if you are taking longer your loosing money. If you bought some sand that was cheap there is a reason, it is not been screened to size that means it can have larger rocks or pebbles in it which can plug up the flow hose or your nozzle.

Some do not under-stand there is a cost factor with better products. Find a source and try it out, check out a couple of bags to make sure it is uniform before starting out on a customers time. Names like play-ground sand, tube sand, play sand, general use sand or "for use in concrete" are tips that the sand is not been screened for larger partials. Look for at least; mortar sand, sandblasting media, or a given size of screening if you want your job to move along smoothly. Paying a bit more for a better will work out better in the long run. Look for the graded or sized sand not just sand unless you want to screen it you would be surprised how much over sized waist there is in  a bag of ungraded sand. You're pay for it by the pound why not get only what you can use?

Sand or slag "chips" away at the surface being removed when it impacts the item sharp edges cut at what is being removed. The larger more aggressive grades will also cut or chip away at the under laying surface too. Once it has chipped it usually fractures into smaller parts reenters the water stream and impacts the surface once again but with less force this process is repeated till the particulars loses enough size or speed and is "washed out". Using too aggressive or grade may have to much impact on the under laying surface leaving it rough or gouged. Picking the right grade will come with time and experience. You need to  start with the finer grades and work your way up a finer grade will still remove the unwanted layer it may take longer but it will be safer till you have figured out your style or technique.

So what can I use we have used river sand, mortar sand and in both cases wound up have to sift it or screen it to remove the larger particulars. We have moved to just buying sand that is bagged and sold for sandblasting treating it as a consumable using it once and then disposing of it.



Coal slag is what is left over after the coal is consumed the part that did not burn up. The oil is consumed and the shell or chaff that is left is ground up and screened for size. This stuff is sharp and really cuts. I like it better than sand, there is also the arguments weather it is as bad as sand if you breath it while using it? Since we are using it as a wet media this point is mute. The water stream keeps any dust from forming. Since coal slag is a waste product I like to think it has this second life so we are getting twice the bang out of it. From my usage I feel you get a better bang form slag it is lighter and seems to flow better. I also feel it is more productive and cost less here, where I work, live and purchase it. We have three different retailers with several locations that sell coal slag in the bag ready to use. Coal slag is of course black and I have heard some call it, black sand, but it is not sand. Sand which is a silicate, coal slag is a carbon. Two different substances but both working in the same way.

Remember these two mediums are "cutter" or "chippers" and are abrasive. Cleaned by Pete use them in and with their wet media blasting service and can tell you what is right for your job call us at 417-459-7869 for your cleaning needs. Picture of this service can be found by click the web link below:
www.cleanedbypete.com
in the media blasting section or in the photo gallery.