Media: Corncob and Corn Cob Blasting

Standard Grades Used: 10/14, 14/20, 20/40 and 40/60

Overview: Vibratory finishing and tumbling are mass finishing processes where the abrasive and absorbent characteristics are generally both desirable. Corncob and corn cob blasting grit polishes and deburs parts and at the same time cleans and dries parts. Oils and other liquids from wet mass finishing processes are absorbed. Grade selection is typically based upon the finished surface profile desired and the diameter of any holes or cavities in the part. The selected grade should not contain particles that would lodge in part openings.

Grit blasting with corncob and corn cob blasting particles is accomplished with the same equipment as used for sand blasting. Because corncob and corn cob blasting grit is considerably less aggressive than sand, it is often categorized as a "soft abrasive" (corncob and corn cob blasting grit has a 4.5 Mohs hardness). corncob and corn cob blasting grit does not etch glass or foul bearings and is frequently used to clean electric motors and machinery with hydraulic cylinders. Other applications include: smoke damage and residue clean-up; mold cleaning; plant maintenance; and loose and flaking paint removal. It is ideal for wood, aluminum and fiberglass substrates.

Unlike mass finishing processes, blasting with corncob and corn cob blasting grit is not as predictable. Each job tends to have unique characteristics which do not allow for estimating precise media usage or outcomes. We recommend testing a couple of grades to determine which offers the best performance. We will box and ship 40-pound bags anywhere in the USA for $40.00 per bag.

Remember to flush any other media from your equipment before performing the test.

First, why crushed corncob and corn cob blastings?

Well it seems it will clean wood without really removing or damaging the wood. The ground up cob is just about equal in hardness to most of the softwoods typically used in log cabin building.  On the MOHS  hardness scale both range between 2 and 4.5 (big difference due to so many different types).  It does a good job and the waste can just be left on the ground to disintegrate - it helps, not hurts the environment.  For you fully naturalist log cabin owners you can put it in your compost pile!  That is assuming you did not paint your cabin with a lead base paint.  The most often recommended size for blasting a log cabin is our 40/60 grit. 

What's it going to cost me?

$25 (US) per 40 pound bag of 40/60 corncob and corn cob blasting grit, plus packaging and freight from Portland, OR 97267  Plus the cost of renting a blast pot and compressor.  The freight cost will vary depending on where you are and how much you need.  You might be looking at $10 to $20 or more per bag.  If you require less then 5 bags you might find that UPS is a good method.  You can find out how to get a price from UPS on the internet by clicking here.  Bags of corncob  and corn cob blasting grit are ? x ? x ? and weigh 40 pounds each.  When shipping via UPS we wrap each brown paper bag in shrink wrap to protect it, you need to add $5.00 per bag for this - we do not put it in boxes.  If you want more than 5 bags then putting it on a pallet and shrink wrapping the whole thing, then shipping via commercial freight carrier is the way to go.  We charge the $25 per bag plus $5 for a disposable wood pallet and another $5 to shrink wrap each pallet.  You do not pay the $5 per bag packaging fee when shipped on a pallet.  We normally place up to 50 bags on a pallet.


How much will I need?

Now that is the big question, no one seems to really agree and the reason is that the variables are many.  The amount you need will range from 2 pounds per square foot to 10 pounds or more per square foot.  It depends on what you have to clean off, the size of the nozzle and blasting hose, the air pressure and volume of air. For a normal cleaning to remove mold, light paint or weather stain I suggest that you start with about 4 to 5 pounds per square foot (one bag for every 200 sq ft) of blasting area and go from there. 

Crushed corncob and corn cob blastings are made from the woody ring portion of the corncob. This portion of the cob is separated, dried, ground, air-cleaned, and then classified over screens of various mesh sizes.  They are available in granules ranging from 1/4 to a fine powder.

Qualities of crushed corncob and corn cob blastings that make them ideal for pressure blasting include its mild abrasiveness, absorbency, and resilience to attrition.  Advantages of using corncob and corn cob blastings for blasting include the elimination of masking, elimination of solvents and pollution concerns, non-sparking and non-toxic operation, non-silica content, and the fact that it is organic and biodegradable. 

  Common applications of corncob and corn cob blasting include:
  • cleaning of motors, generators, and heavy equipment
  • cleaning of insulators and transformers
  • removal of manufacturing soils from the ceiling of industrial facilities
  • cleaning of pipes and pumps in processing plants
  • cleaning and paint preparation of buildings
  • cleaning of timbers in log homes prior to sealing
  • cleaning of boat hulls
  Crushed corncob and corn cob blastings have a 4.5 Mohs hardness and are available in the following standard sizes:
Size Passes through: Retained on:
814 #8 (.0937) #14 (.0555)
1420 #14 (.0555) #20 (.0331)
2040 #20 (.0331) #40 (.0165)
4060 #40 (.0165) #60 (.0098)


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