Briarfox wrote:... I've been doing some research but I've been unable to find out how course of a glass bead I want for blasting? What are the benefits of course vs fine?....
Good question, and one I'm still sorting out. I think your going to need to experiment with it yourself, but I'd cetainly be interested in any incite others might care to share.
I've got #10 and #12 glass bead, but only used the #12. It's maybe a little too fine, but I'm not unhappy with it. My next step will be to try a smaller nozzle as the one that came with the unit seems a little too wide for this fine a media. I also think I can work the grain a little more with a narrower stream. The finer grit seems to facilitate a lot of detail in the blast, but I don't know at what cost.
The grit and nozzle need to match up, so to some extent your limited by that on the coarse side of the equation (your nozzle size is limited by how much air compressor you have, in terms of if it can keep up). It's a matter of fine tuning the process based on your set up, the briar, and the type of blast your after. For instance, Jim Cooke uses three separate medias and at least two different nozzles.
I've blasted enough on a system I had no control over to realize that a lot is the wood itself. Some pieces just seem to blast great in spite of all the limitations, while others seem to refuse to yield no matter what you shoot at them
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