Question on BP size

[cornbelt]

FFFg 20 mesh 3% 50 mesh 12% The question is, "What do the numbers mean?"

[indian joe]

FFFg 20 mesh 3% 50 mesh 12% The question is, "What do the numbers mean?"

first number means 3% will stay on top of a 20 mesh screen the rest will pass through it (so 3% of that sample is really FFsize kernels)

Second number means 12% will pass through a 50 mesh screen the balance is retained - (so 12% of your sample is FFFFG or fines) thats too much for my liking but FFFg is the main seller so it gets the widest spread I guess

Also remember this is an industrial process - if you take the same powder, same screens and you shake it harder or for longer or both - or less - then the result will be different .

[cornbelt]

Thank you! That makes the whole table from page 48 of the BP chronology make sense.

[Geezer in NH]

Get your own screens here

http://www.akmining.biz/cart/tyler.htm

Most bench slug gun shooters screen their powder to shoot competition.

[indian joe]

Get your own screens here

http://www.akmining.biz/cart/tyler.htm

Most bench slug gun shooters screen their powder to shoot competition.

or you can buy stainless mesh sheets cheap off ebay and make em up in pine 2x1 frames.

I screen my FFFg at 24 to 40 and I shake it till it stops running - FFg gets 16 to 24 - Fg is 12 to 16 ----that gives us quantities of each that we get used at about the right rate

[cornbelt]

Thanx for the info on screens. I have a stock of 2nd hand rea strainers, but there's gotta be a better way.

[indian joe]

Thanx for the info on screens. I have a stock of 2nd hand rea strainers, but there's gotta be a better way.

kitchen section of the grocery store will get you 12 mesh strainer , 22 or 24 mesh splatter screen, aluminium window screen is 16 mesh, .....40 mesh I had on hand from crop spraying gear but the ebay stuff is ok.

[cornbelt]

I've been using a splatter screen. Its good for 3F and dust, but I get more dust than anything. Would casin make the grains harder and less dusty?

[LAGS]

I bought a set of sifting screens off Ebay.
They run from 10 down to 60.
I shoot mostly 3f.
So what passes thru a 30 screen but will not pass thru a 40 screen is what I use for 3f.
For 2f , what passes thru a 10 but holds on a 20
Anything that holds on a 10 , I consider 1f.
Now what passes thru the 40 but won't pass a 50 works great if I need 4f.
But what holds on a 60 works for 4f also, but to me is almost Dust and blows around a bit
But what usually passes thru a 40 , ( which there is Lots of ) gets Re Dampened and either gets Represses and Corned , or just Re Screened then resifted when it dries out.

[indian joe]

I've been using a splatter screen. Its good for 3F and dust, but I get more dust than anything. Would casin make the grains harder and less dusty?

Are you pressing pucks (hydraulic press) ? If so let em dry properly (talkin weeks not days for that)
If you just screening your powder to make the grains then yes some dextrin will help with grain structure - I actually get less % of fines and dust with screening than with busting pucks but the density of the finished powder is better with pucks. A splatter screen is about 22-24 mesh and the wires are fine, a LOT of FFFgrade will go through a splatter screen

[cornbelt]

I've been pressing wafers in a die between termite shield discs; about a teaspoon between each, so they come out pretty thin and easier to break up. For drying, I use a convection oven after I get it screened to size.