The Benefits of Crushed Glass Grit

Here is an excerpt of a great rave by 'MasterBlaster' from on contractortalk.com on the benefits of Crushed Glass Grit:

"...Crushed glass is by far the Greenest and safest of all blast media's available today.

Crushed glass has a super small carbon footprint..... because it's made from 100% post consumable products as in "recycled glass".... this is same stuff you put out at curbside for recycling pickup.... and in most cases recycled glass is produced, recycled and packaged within 50 miles of where it's being used....while other products like olivine, garnet and star-blast have to be mined, processed and shipped hundreds and or thousands of miles to get it to market and in those cases use valuable fossil fuels to get it to market... "recycled glass is the GREENEST and CLEANEST product available today and uses very little fossil fuel to produce."

Crushed glass is also considered the waste product of the glass recycling industry.... again when they recycle glass they recycle it for the larger pieces which are separated by color (Which saves energy... because when you start with COLORED GLASS to produce COLORED CLASS it saves a lot more energy and fossil fuel) also the crushed glass we use can't be separated by color so it's the waste product and before we used it for media blasting it use to go directly to the landfill... (So by use using it for media blasting they found another use for it and YET ANOTHER USE FOR THIS RECYCLED PRODUCT as in media blasting.... AGAIN THE GREENIES LOVE IT AND EAT IT UP.

As far dust goes... recycled glass produces a lot less dust especially if you're doing wet abrasive blasting... and while it's always a good practice to do containment on all you job to prevent your media from getting on the ground.... the one thing to keep in mind is recycled glass 100% inert so what gets on the ground is relatively safe and isn't considered a contaminate like Black Beauty, Soda and or steel shot... it doesn't change color or contaminate the ground, it doesn't kill plants or wildlife and it blends into the ground like granular dirt... not that I'm saying it's ok to leave any waste behind, but yes it blends in well..."

The full post and the related string can be found on contractortalk.com.

Silica and OSHA

The Occupational Safety and Health Administration (OSHA) is in final preparations for a hazard communication related to a Occupational Exposure to Crystalline Silica. This rule will basically set standards for exposure to silica dust during blasting (and other operations) in confined work spaces. Inhalation of silica is generally considered to increase the risk of silicosis.

According the OSHA, in 2005 "silicosis was identified on 161 death certificates as an underlying or contributing cause of death. Exposure to crystalline silica has also been associated with an increased risk of developing tuberculosis and other nonmalignant respiratory diseases, as well as renal and autoimmune diseases." The need for the exposure standard is the standardize monitoring, training for use with silica and compliance.

Of course, in an abrasive blasting environment the best way to avoid the hazards of silicosis is to use media that do not contain crystalline silica such as Crushed Glass Grit.

Auto Blasting with Glass Grit

Coatingsguy (thank you!) posted a couple of great before and after pictures of an auto restoration blasting project. The van in the picture above was stripped and ready for priming after blasting with Fine Crushed Glass Grit. Per his comments (link below), the van required 5-1/2 bags of media and 4 hours.

Here is a link on contractortalk.com. Thanks again for sharing.

Crushed Glass - Gulf Coast Project

PaintSquare News recently posted an article - Uncontained Blast Medium OK'd for Gulf Coast Project - about the use of Crushed Glass Grit to remove a vinyl coating on a concrete surface. The US Army Corps of Engineers approved the use of this medium for abrasive blasting without containment since the Crushed Glass Grit does not contain free silica or toxic chemicals.

The article does a nice job of explaining the project and what issues needed to be considered prior to approval. Safety of the workers and the area surrounding the project were of prime importance.

I think the most interesting part of the article is the long discussion in the comments section. Ultimately, there really is no other reasonable option than to blast the surfaces. While concerns are raised regarding issues with potential hazards in the coating and with blasting concrete, the best choice for this project (and others like it) is Crushed Glass Grit.

Abrasive Blast Rooms

Abrasive blast rooms offer a lot of advantages when blasting large parts and when using a re-usable media such as Aluminum Oxide or Steel Shot. These rooms provide an area that can collect the media, send it to a recycling and separating system and then be re-blasted. Blast rooms can also be equipped with exhaust and dust collection systems. The major drawback is the cost typically in excess of $100,000.

An alternative to a blast room is to perform the abrasive blasting in either an outdoor area that is 'closed' in or to blast in a separate room such as a garage or shipping container. These areas can be set up to contain the media and dust but will limit the media choices to consumable, less expensive blasting media such as Crushed Glass Grit.

In order to use a re-usable media, a system such as the Blast Room Package is needed to collect, separate, clean and blast the media. Simply sweeping the used media, dust, dirt, paint chips, etc. into a feed hopper will transfer the recycled material to the abrasive separator, clean out large pieces, remove the dust and send the good media to the pressure pot for re-blasting. The Blast Room Package can simulate nearly all the benefits of a full-fledged blast room but at a fraction of the cost.

Crushed Glass Grit vs Coal Slag

ContractorTalk.com is a great resource for contractors looking for help from their peers on a variety of topics. There was recently a thread started by a contractor that uses coal slag who was looking for other user's preferences as well as similarities and differences between Crushed Glass Grit and coal slag. Some of the comments included:

"I use the glass because of the area I am in...Maine is going greener..."
"I use coarse glass on heavy rust and heavy equipment"
"'Medium grade good for autos and bikes"
"Glass cleans faster...large media for heavy scale and rust...fine for everything from log and cedar homes to thin sheet metal auto panels"
"My {powder} coaters like glass because it is clean and takes very little prep work before coating"
"I used to use slag and it's filthy. Even my hands were dirty from being around it."

Coal Slag

When coal is burned in a boiler to produce energy, the incombustible materials constitute three components: fly ash, bottom ash and bottom slag. There is growing concern about the potential hazards of coal waste due to contamination with heavy metals such as chromium, lead and arsenic.

Fly ash is the light 'dust' that is exhausted from the burning process. Improvements over the past 20 years at coal fired facilities has allowed as much as 99% of this ash to be captured for re-use in other applications. Bottom ash is the unburned material and fine particulate that is not expelled in the flue. A recent 60 Minutes expose discusses some of the hazards of fly ash:

Watch CBS News Videos Online

Boiler slag is the molten material (ash and incombustible) that is sent to a quenching water bath. The quenching process immediately fractures the molten material producing a coarse, hard, black, angular, glassy material sometimes call black beauty. This coal slag is used for a variety of industrial applications including abrasive blasting. The concern is that once the coal slag is blasted, the process releases the heavy metals into the air or they get absorbed by ground water.

While coal slag (which contains minimal crystalline silica) has historically been considered to be a safe alternative to silica sand, the EPA is reviewing whether to classify fly ash and other coal burning wastes as a hazardous material. There is no need to wait for the EPA to make a final determination. There are many alternatives to coal slag for blasting such as crushed glass grit and other more specialty types of blasting media.

Recyclable Abrasive Blast Media

Many types of abrasive blast media can be re-used multiple times. The rate at which the media fractures during blasting will determine the recyclability. Media such as Steel Shot have an extremely high re-use rate while more consumable media such as Crushed Glass Grit can only be blasted once or twice. This chart details the recyclability of many common abrasive blast media.

Some factors to consider when selecting a media (as it relates to re-usability):

• Blasting system: Blasters that automatically collect the media (i.e., cabinets, blast rooms) make it much easier to use recyclable media.
• Cost: Typically, re-usable media are more expensive to purchase; however, the re-usability can make these media very economical.
• Surface finish: The hardness and aggressiveness of the media is not directly related to re-usability. Consider the surface finish required in combination with the recyclability.
• Cleanliness: Collected used media can also include contaminants that can reduce efficiency (i.e., dust particles), impact blasting performance (i.e., paint chips blocking the nozzle) or even damage the surface (i.e., concrete chips or small stones). Be sure to screen and clean the media as best as possible.

Thin Aluminum Blasting

Using abrasive blasting for auto restoration can be a very challenging process due to potential warping of the thin metal panels. Many different blast media can be used such as Walnut Shell Grit, soda, Plastic Abrasive Media, sand and Crushed Glass Grit. While each of these media have different benefits, Crushed Glass Grit is growing in popularity for this application.

While the abrasive media being used is critical, the blasting procedure itself is just as important. The soda can -used to simulate a thin car body panel- on the left was blasted with Fine (70/100 mesh) Crushed Glass Grit at 60 psi. Notice the excellent stripping of the printing but also the warpage and deformation on the thin aluminum. The can on the right was blasted with the exact same media but at 30 psi. The stripping result was also excellent but there is no indication of damage to the metal.

While Crushed Glass Grit is a media generates heat during blasting (like coal slag, sand, garnet and others) which can warp thin metal, the process used by the operator to provide a quick strip rate -typically faster than Walnut Shell Grit and soda- is as important to achieving successful results.

Crushed Glass Grit - Uses (2)

Both Medium (40-70 mesh) and Fine (70-100 mesh) Crushed Glass Grit can be used for many different applications. Below are examples of some of the more popular uses - some may even surprise:

Medium Crushed Glass Grit

• Auto restoration - rust removal, more aggressive than soda
• Log home - rough hewn logs, aggressive on wood
• Masonry restoration - brick, cement block
• Tanks - mill scale removal
• Graffiti removal - concrete, asphalt (no damage on surface)
• Consumer - metal (iron): lawn furniture, fencing, decking

Fine Crushed Glass Grit

• Log home - smooth finish, alternative to Corn Cob Grit
• Aluminum surfaces - no pitting, good strip rate
• Auto restoration - body panels, engine parts (smooth, etched finish)
• Boats - fiberglass, no media embedding
• General parts cleaning - less than 1 mil surface profile

Obviously, the list of potential applications is much longer and limited only to the imagination and expertise of the user. Please share other applications in the comments section.

Crushed Glass Grit - Uses

A quick list of applications and uses for Coarse (10/40 mesh) Crushed Glass Grit:

• Bridges - heavy paint and coatings
• Tanks - outside welds, rust
• Pipelines - rust and oxidation
• Water towers - paint, rust
• Ship hull blasting - welds, paint, oxidation
• Barges - clean-up, surface preparation
• Heavy, industrial equipment - tractors, front-end loaders, snow plows
• Structural steel - surface profiling, oxidation removal

Coarse Crushed Glass Grit can be used for many applications and reasons (not just the short list here). The 10/40 mesh size is the most aggressive and can provide a 2-3 mil profile on many surfaces. Please share your experiences with Crushed Glass Grit in the comments to this post.

A list of applications for the finer sizes to come on the next post.

Crushed Glass Grit Benefits

Crushed Glass Grit offer a number of environmental and performance benefits:

• Sourced from 100% recycled bottle glass diverting material from landfills
• Non-reactive and inert it and can used near water
• OSHA/NIOSH classified as 'nuisance' dust
• No silica
• No heavy metals
• CARB approved for outdoor blasting under Title 17
• QPL approved for Military under MIL-A-22262B
• Low embedment in surface
• Can be used in both we and dry blasting operations
• Multiple grit sizes for heavy stripping on tanks, bridges and heavy steel to sensitive blasting on wood, fiberglass and thin metals

Abrasive Blasting Media - Crushed Glass Grit

Traditional sand blasting and the need for healthy and environmentally sensitive operations meet up perfectly when using Crushed Glass Grit. Glass has the same hardness and other blasting properties as silica sand but none of the inhalation dangers from free silica. Crushed Glass Grit is 100% recycled glass diverting this material away from landfills.

Crushed Glass Grit is available in a wide variety grit sizes making it suitable for many different applications. Coarse sizes can be used for heavy duty stripping of paint, rust and other coatings off structural steel, concrete, brick and other structures. Fine sizes can be used (if careful) on thin metal surfaces such as automobile door panels without warping and even on wood surfaces without etching.

With recent performance and environmental approvals from the military and government agencies, Crushed Glass Grit is increasingly being used as a replacement for coal slag and other 'dirty' media. As Glass contains no heavy metals or free silica this media is showing increasing versatility as an economical, consumable blasting media.

Glass Bead vs. Crushed Glass Grit

We get a lot of questions about the difference between Glass Bead and Crushed Glass Grit. Below are some before and after pictures of a copper pipe after blasting with similar grit sizes of both of these materials. [Note: The pictures are not great but you should be able to see some clear differences.]

Welding burns & discoloration on surface

Glass Bead is a round particle that produces a very smooth, satin-like finish. This media can be re-used multiple times and is typically used in a blast cabinet. Crushed Glass Grit is an angular grit that offers very good strip rates but breaks down very quickly. Crushed Glass Grit is generally used in portable blasting equipment where collection and re-use is difficult.


Glass Bead - Bright, smooth, satin-like finish


Crushed Glass Grit - Lightly etched finish, very short blast time

Crushed Glass Grit

The 'hottest' abrasive blast media right now seems to be Crushed Glass Grit. This media is sourced from recycled glass - mostly bottle (beer) glass. It is generally a mixture of clear, green and brown glass. Crushed Glass Grit has lots of great advantages:

• Clean, white-metal finish
• No free silica, heavy metals or other contaminants (like in many coal slags)
• Angular shape offers quick stripping (similar to silica in hardness)
• Cost effective use

Two issues to keep in mind when using Crushed Glass Grit: (1) Media is considered consumable and is not generally re-usable; (2) Source quality can vary dramatically - we use New Age Blast Media.

What experiences and performance have you had with Crushed Glass Grit?

Blast Cleaning Steel - Pictures

I posted some information a few weeks ago about using Crushed Glass Grit to strip/clean steel. Here are some before and after pictures using Coarse Crushed Glass Grit on a cast iron part to remove some moderate to heavy rust. The total blast time was less than one minute and the total surface area is about 1 cubic foot.

Blast Cleaning Steel

Historically, steel has been blasted using silica sand. For obvious health reasons (potential silicosis hazard), silica is not a safe media to use. Many industrial contractors, municipalities and military facilities are now using Crushed Glass Grit to blast steel.

Crushed Glass Grit will remove paint, dirt, soils and rust leaving a 'white' metal surface. Depending on the grit size used, a micro-finish can be achieved so that the steel can be immediately primed and painted with no further preparation.

Produced from recycled bottle (mostly) glass, Crushed Glass Grit contains no free silica, heavy metals and is approved in many of the most stringent air quality districts. Crushed Glass Grit is also considered a green blasting media since it is 'neutral' to the environment.

July 4th BBQ

Take a look at your wood deck or concrete or stone patio while you are grilling over the weekend. Does the surface need some attention? A few tips to begin the cleaning and restoration process:

Wood Decks -- Dry abrasive blasting with Corn Cob Grit can strip dirt, soils, stains and coatings without damaging the wood or raising the grain. Avoid harder media such as sand (don't ever blast with silica sand anyway) or glass or coal slag as these will definitely etch the wood and can cause damage. The main benefit of dry abrasive blasting versus high pressure water is that the dry surface can be re-sealed immediately - a one weekend project instead of two or three.

Concrete or Stone Patios -- Stripping paint off concrete surfaces requires a more aggressive abrasive such as Crushed Glass Grit. Stone which can be softer than concrete might demand Crushed Glass Grit but Walnut Shell Grit may be a better option since it is not as aggressive and stone is easier to clean (typically no paint or coatings to remove).

Final tip -- Enjoy the BBQ first, then start the work!