Hurricanes, Oil & Shipping

It is absolutely upsetting to see the pictures and read the stories of those affected so dramatically by the hurricanes in the Gulf of Mexico. The devastation in some of these communities seems irreversible.

A silver lining with these 2008 storms is the minimal damage to the oil refineries in the Gulf. The anticipated but un-materialized damage to infrastructure has taken some of the crazy speculation out of the global oil market.

With the price per drum dropping below $100 per barrel from a high of nearly $150 I suspect that the inflationary pressures on many products will weaken. More importantly the cost of shipping and fuel surcharges should start to come down - although I'm sure not as quickly as they went up in the past 12 months.

Tumbling with Abrasive Grit

Tumbling parts to achieve a deburred, deflashed or rounded edge is a common process. Both vibratory and barrel tumblers are used for this purpose. Choosing the proper media type is critical to achieving the desired finish.

Most applications require the use a preformed tumbling media. These media contain abrasives that are released into the tumbling process to remove the burr, etc. The (relatively) large mass of the media assists in this process by acting as a sanding block of sorts on the edge and surface of the part. After this abrasive process, parts can be tumbling in other media (including grits) to achieve a smoother or polished surface finish.

Tumbling parts simply with an abrasive grit such as Aluminum Oxide, Silicon Carbide or Walnut Shell does not typically achieve the deburring, deflashing or edge rounding required. While the grit may be very sharp, hard and abrasive, there is very little force acting against the edge of the part. The surface finish will probably be affected (roughening, smoothing or even polishing) but the edges will be left mostly untouched.

There are some exceptions to this 'rule' (see this post) but generally preformed tumbling media is superior to grit media for deburring, deflashing and edge rounding.

Log Home Blasting

Here is a great picture of a do-it-yourself log home blasting project. The blaster being used is a relatively small KF100DM Portable Pressure Blaster with a 3/16" nozzle. Fine Corn Cob Grit is the media being blasted. The objective was to take off the old stain and sealant so that the logs could be re-stained and sealed. I believe the job was completed in one weekend.

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

Beijing Olympics

Wow! An impressive show by the Chinese with these 2008 Olympics. Many of the controls the government put in place to control pollution (stopping construction, closing factories, significantly reduced traffic) seemed to work - although a couple days of well 'placed' rain also helped.

A couple of random thoughts now that we are beyond these Olympic games:

• China spent A LOT of money on these games. While impressive, most of this $$$ came from western countries buying less expensive Chinese goods (one individual purchase at a time) leading, of course, to China's continuing economic growth. Is this really best for our local and global economies?


• Construction and factories were shut down across China to reduce horrible pollution for two weeks. Now that the Chinese have seen what a blue sky looks like again, I wonder if there will be any continuation of this environmental policy. If the Chinese return to the pre-games norm, I suspect that pricing and supply pressures on many materials (Aluminum Oxide, Silicon Carbide and Steel among many others) will be back in full force along with the pollution it generates.

London 2012 has a very tough act to follow. I hope that the world has learned important lessons about balancing the environment, global trade policies and individual consumption to springboard our (collective) path towards a better future.

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?