Norwest Posted July 30, 2015 Posted July 30, 2015 Hi, I have a set of screens/classifiers that I used for gem and gold hunting which I would like to use for pyro materials processing. These screens have round green plastic frames which fit into 5 gallon buckets. Any suggestions on how to determine the mesh size? The frames do not have any markings and the funky hardware store I bought them from did not have the models or mesh sizes marked and they are kind of "your on your own" regarding product details. I have seen the Sieve Sizes PDF on the site so that will help. I can measure the larger mesh sieves with ruler but when it comes to the fine mesh I am not sure what to do. Can I use some purchased uniform sized materials to test size? If so any suggestions what to use? Also are there suggestions on what mesh sizes are "must have" for black powder and star comps? I can certainly buy some new screens but I have too mush stuff already and am running out of space Thanks, Norwest
ddewees Posted July 30, 2015 Posted July 30, 2015 You might be able to count the "ticks" running a pin over the screen. Just measure off one inch. Anything finer than 40 will likely be difficult.
mikeee Posted July 30, 2015 Posted July 30, 2015 What does mesh size mean? Determining mesh is very simple. Simply count how many openings there are in one inch of screen. The numberof openings is the mesh size. An 80-mesh screen means there are 80 openings across one linear inch of screen. A 140-mesh screen has 140openings, and so on. Therefore, as the mesh number increases, the size of the openings decreases. Note - Mesh size is not a precisemeasurement of particle size because of the size of the wire used in the screen. Beyond 400 mesh, particle size is normally defined only in"microns." That is because the finer the weave, the closer the wires get together; eventually there is no space between them.
Norwest Posted July 31, 2015 Author Posted July 31, 2015 Great thanks. The pin idea sounds doable. I don't think any of my screens are finer than 40 mesh. How fine do I need to go for BP and star comps?Norwest
ddewees Posted July 31, 2015 Posted July 31, 2015 20 and 40 will be your most used screens. 40 mesh for making sure things are fine enough, 20 for general mixing. That will get you by... Others probably do things slightly different.
Mumbles Posted July 31, 2015 Posted July 31, 2015 If you plan to make your own BP, some slightly larger screens will help as well. At bare minimum I'd suggest 4, 12, 20, and 40 mesh. Something in the ball park those sizes will work fine. The 4, 12, and 20 are useful for grading black powder or granulating compositions. The 20 and 40 are useful for mixing compositions. If you were looking for common items to compare to, salt will be about 30-40 mesh. Beach sand is probably around 20-30 mesh or so. Window screens are around 16 mesh.
Andres1511 Posted July 31, 2015 Posted July 31, 2015 I screen my star comps with 100 mesh.... I like everything fine .Granulating BP = 8 mesh (pretty fine BP).Screen slicing stars = 4 mesh. I recommend the pin method.
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