Cleaned by Pete: what a power washer does: wet media blasting

Showing posts with label wet media blasting. Show all posts

Friday, May 3, 2013

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.

Thursday, April 11, 2013

Media...... What is the difference? sand, soda, coal slag, walnut...

This is a follow up entry to the blog's entry on Media Blasting. I am writing this as only a person who has used the wet media blaster and what I have found out about using it with the different medias. I have not done a doctoral theses on the subject and some may not agree with all of what I have written. This is my opinion and observations from using the product with the wet media blasters Cleaned by Pete owns and uses. We have specialized in doing jobs and items that other sand blasters do not want to do for reasons of time, cost, size, to much labor, or are too odd. Clean by Pete works with each customer to see if we can help fit what you want with what we do.

Wet media blasting is defined as: the process of removing unwanted material with a water stream into which a media is mixed and is contained that throws abrasive particles against the surface with some force causing removal or the unwanted material.

"Media" is the product we add into the water stream to do the removal of the unwanted material, this media can be abrasive or nonabrasive. Depending on what is being blasted and what is being removed you will need the right type of media for different jobs. Wet blasting can use sand, coal slag, crushed glass, soda, walnut shells, and other different media. Then in each group different types or subtypes in each of these categorize and then the different grades of each. These are just a few of the media products that can be used. I will talk about the ones we use.

Are you looking for a factory finish?

Soda Blasting; first soda is also a cleaner, this make the soda media great to work with, for cleaning or using it as a material remover. Anything from removing grease and grime to removing paint and other materials, soda has a lot of uses in the cleaning field. Soda can be purchased in several grades the coarser the grade the larger the particulates are. The larger particulates cut faster and "explode" more removing material quicker but the coarser the grade the more the cost. Soda is a nonabrasive and can be used for blasting where sand and slag and other media can not. You can wet blast a motor compartment of a car with out worrying about the ball joints, steering knuckles or other moving parts. Soda will not hurt, inbed or alter the metal surfaces. This saves time and money you need not have to dismantle everything, it also washes clean. Soda will not hurt or etch chrome, glass or soft rubber surfaces. Soda is great for fire restoration and cleaning if you can get the water removed.

I used the word "explode" earlier, I'll try to clarify this term. Each type of media has its own reaction to the sudden stop when it hits the material it is trying to remove. Soda happens to be soft enough to blow apart upon impact. Sand, glass, and slag are harder they will fracture using sharp edges for cutting off or digging in, to remove the material. Soda impacts and the energy form it blowing apart removes the material like a little explosion or as a meteor hitting a planet a crater is formed in the material blowing it apart. Then the smaller soda particulates will be caught up in the water stream again and the process is repeated until the soda looses all its stored energy, until it is ineffective anymore. The big plus with soda is that it has been tumbling and bounces around all this time. The busted up particulates are like little erasers and pick up more and more grease and dirt, that is why momma uses it to clean the stove and sink in the kitchen it cleans and does not scratch.

A fine nonabrasive soda was used here. We did not want to alter the factory finish of the rims. Soda comes in different grades (sizes of particulars) the coarser the grade the faster it removes but the higher the cost.

You can see still see the milling marks on the face of the wheel and the pebble finish inside the wells. When restoring a car to a factory finish you can not alter the metal surface. Sand and slag would have erased the milling marks and may have gouged in removing metal too. Walnut shells were too large and can not get into and clean the pebbling. Fine soda is what was call for here.

When a car's total restoration counts, some people will spend a great deal of time and money finding the best correct parts. They don't want that distorted or blasted away. Soda blasting this rim will bring it back to factory specs, plus the water stream is clean and washes years of neglect and dirt away away.

Since we are here and are talking about car rims here are a few we have done for a BMW enthusiast. They restore one BMW a year and then "turn it" and move on to the next one. Sometimes these cars have rims we can help with. Here are two of them we have done. Moist of the "sand blaster" in town did not want to touch them told them they would distort or ruin the rims before they could get the power coat paint and the baked on clear coat off. The owner said one blaster said he would do it but he didn't really trust him. Here is what Cleaned by Pete did with them.

Removing the factor power coat and baked on clear coat for a restoration on a BMW. We had to use a two step process with different types of media to achieve this result.

Media blasting with water and soda Cleaned by Pete.

In this close up you can see the paint and factor finish is removed we are down to the original factor metal and have not distorted any fine details. The owner told us these are magnesium centers and are hard to find, that is one reason why no one wanted to blast them.

You can see that the factory power coat and finish is wearing off the turbo style centers. Again the owner came to us since he had such good results with us on the first ones. We used the same two step media process to restore these centers too.

Readying the center for the wet soda blasting, we have a soft plastic backstop to help absorb the energy reducing bounce back and splattering of the media (tricks of the trade) helping us to work faster and more effective.

The group have been blasted once and will now be having the finial grade of soda blasting applied.

After the process and the drying time our BMW center looks like. This is now down to the original finish of the metal before being power coated and clear coated, without gouging or distortion of any kind.

A bit closer picture showing the finished item Cleaned by Pete's Wet soda-blasting service.

I will end this entry here and pick up when, Cleaned by Pete soda blasts a '55 Thunderbird rear end in the next entry. Seeing that I have a lot to cover I'll break it up in smaller parts and entries. Let us know in the comment box below about your work with "wet blasting". Thanks for the viewing.

Thursday, April 4, 2013

Attachments: the "Media Blaster"

Media Blasting, Sand, Coal Slag & Soda

As promised this entry is about our media attachments, yes attachments we have two different types, which we use for different needs and jobs. When first setting up and studying on this entry up I found out there is to much information to cover in one short entry so I am going to break it up a bit and today hit the highlights and then go into a bit more in the later entry or entries.

There are several "pluses" and "negatives" of each method or for "Dry VS. Wet" blasting. I will touch on these points and different media in the later blog entry. For now we will discuss the attachment and how and why it works.

Media can anything that can be drawn into the water or air stream. Common media can be screened sand, coal slag, crushed walnut shells, cobs, soda, crushed glass and other products, each of these have different cutting abilities and come in different grades in-order to fine tune your job's need. Wet media blasting or wet sand blasting is using our pressure washer to supply the water stream and the pressure needed to push this media to the unwanted material and remove it. Some of this media is made to cut off that material, some is made to roll thus more or less erasing the material, and then there is some that hit and fracture or explode removing the material more in a later blog entry. The first thing it to get the media into the water stream.

This is the mixing nozzle that draws in the media and them mixes it into the water stream. Picture form Cleaned by Pete

These tips have to be fit to the power washer as are all nozzles we use, as we learned in earlier entries to big of nozzle reduces pressure to small causes other problems and can harm the pump. This nozzle has a tungsten insert to reduce ware form the media (the one pictured below has a ceramic / metal tip combination). In order to draw the media into the nozzle we have to create a low pressure zone. This low pressure zone is created inside the nozzle it will be filled by air being drawn in and in that air will also be the media drawing it though the pickup hose. Drawing different media takes different pressures the nozzle above does not adjust for media flow, so we made special inserts to put into the hose drawing the media to help draw at different rates for different medias. The setup below has an adjustable flow there is a small lever on the side-handle which helps to regulate the draw of different media. To much media in the water stream will slow down the blasting process and will not work as effective, and has more waste.

The small lever on the side handle will help to adjust the media flow, Cleaned by Pete

That is the simple description and function of the media blaster. I will have more on it later in following blog entries as well as different media we use for blasting and why. The following pictures are the media blasters we use, and our setup.

This is a 16hp motor with a 4 gpm @4000 psi nickle plated head AR pump, the tank on the side is a simple hopper to hold the media or we can use it out of the bucket on the right. Photo from Cleaned by Pete

Cleaned by Pete's media blasting washer.


Cleaned by Pete's Landa media or sand blasting wand and sand probe setup.

The below pictures are of each unit the first one we had set up for soda blasting though we can use it for sand and other media it main job is for soda blasting. The other unit is made by Landa and we use it for all other media we use in blasting.