DUTLESS BLASTING DB1500, User Manual

Page: 23 / 26

A common misconception is that the coarser glass will help you get through a job faster. It is true that 20/40 glass is
slightly more aggressive than 40/70. However, because it's so coarse, you're only getting half as many particles of glass in
the same size bag. You'll end up using twice as many bags to get the job done, which is not only expensive, but inefficient!
It's a much better idea to increase abrasive density if you want to complete the job faster.
ABRASIVE DENSITY
Understanding the weight or bulk density of the media you are using will also help decide which is best for the process.
The heavier the media, the more impact it has on the surface you are blasting. Imagine a golf ball and a ping pong ball.
They are the same shape and size, but the golf ball is more dense. If you threw them at someone, the golf ball would hurt
a lot more.
Crushed glass has a bulk density of 75-80 lbs per cubic foot— while garnet weighs around 145 lbs per cubic foot. So, the
two abrasives at the same mesh size and blast pressure will have different results. A 40/70 crushed glass will be more
“gentle” on the surface than the same mesh size of garnet at the same blast pressure.
The harder and heavier the abrasive is, the rougher the profile will be. Using larger, more coarse abrasives will decrease
the run time in your machine. For example, if you are blasting with 40/70 crushed glass and decide to use a larger mesh
size of 20/40 you will notice a decrease in run time. If both bags of abrasive are 50 lbs, there are fewer particles in the
20/40 mesh size bag than the 40/70. A larger mesh size will be more aggressive so it will have more of an impact to the
surface you are blasting.
ABRASIVE HARDNESS
Generally, the harder the particle, the deeper the profile it will impart. Softer abrasives, like organic materials and plastics,
are good for removing dirt, oil, grease and paint without removing any of the substrate or creating a profile.
ADJUSTING ABRASIVE SUPPLY
You will need to adjust media flow from time to time, when you are using different types of media or when you are
switching between wet and dry blasting.
When wet blasting, start with outlet pipe 1/2 inch above locked position, and adjust in 1/16 inch increments until media
runs out before water. Coarser media will require a higher outlet pipe setting.
When dry blasting, start with outlet pipe 3/8 inch above locked position and adjust in 1/16 inch increments until you reach
the desired productivity to use ratio. Setting will be closer to 1/8 inch for fine media and up to 3/4 inch for coarse media.
18