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Sieving compositions together, what mesh do you use?


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#1 dangerousamateur

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Posted 07 September 2012 - 06:18 AM

I'm about to buy some steel mesh for mixing compositions.

What mesh size do you prefer for that job? Especially for mixtures that are not going to be ball milled afterwards.

#2 MikeB

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Posted 07 September 2012 - 07:34 AM

I'm about to buy some steel mesh for mixing compositions.

What mesh size do you prefer for that job? Especially for mixtures that are not going to be ball milled afterwards.



First off make sure you buy stainless steel. McMaster Carr has a good selection. For general purpose mixing you can get by with a 40 mesh screen, although you should have 20, 40, and 60. Do yourself a favor and don't make them too small, ie.. 12x12, a 16x24 nominal size is much more serviceable.
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#3 nater

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Posted 07 September 2012 - 09:19 AM

.. Do yourself a favor and don't make them too small, ie.. 12x12, a 16x24 nominal size is much more serviceable.


I wish I would have been told this the first time around. I bought a few 12x12 screens from McMaster-Carr and built frames for them. I like to make 1000g batches of BP for rocket fuel and these screens are too small to be functional.
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#4 Potassiumchlorate

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Posted 07 September 2012 - 09:28 AM

40 mesh. I use a simple spaghetti strainer of metal to sieve 1 kilo at a time ;)
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#5 Mumbles

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Posted 07 September 2012 - 04:35 PM

The small screens work if they have high sides. I made my first set out of plastic shoe boxes with 6" x 12" screens in the bottom. I made numerous multi-kilo batches in them. It wasn't easy, but it could be done. It was all I had really up until my accident and I was regularly making 5-10lb shells with such small things. It can be done. Is it easy, or would I recommend it? Not a chance. Those screens made out of 5 gallon buckets are really only around 10" across and they actually work quite well for batches under a few kilos.

As I rebuild I'm looking into 16" x 24" or 24" x 24" screens. The 24" x 24" screens I've used before easily handle a 25lb batch.

I will second the 20, 40, and 60 mesh screens. The 20 mesh is good for breaking up lumps. 40 mesh is good all around, but I like a 60 or 80 mesh better for colored stars. It removes any debris from red gum and clumps from parlon. I also feel that the mix gets better integrated so you have smoother burns in some cases. That last bit is all personal opinion and not fact in the least.
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#6 Peret

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Posted 08 September 2012 - 12:07 AM

I use 60 mesh, but I generally pre-screen my chemicals individually through 100 mesh first. My Parlon in particular has quite a lot of particles that won't pass 100 mesh.

#7 Arthur

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Posted 08 September 2012 - 02:31 AM

I started with 4" square stainless meshes fused into the bottom of stacking sandwich boxes, one lid and one solid box. Put powder in at the top and take all the size grades out. A stack for grading BP was useful. Bigger sheets of mesh are better for big production runs. There are stacking boxes that will take 12" squares of mesh to be found in the UK.

Small star projects need finer powders so 100mesh for really tiny stars, but probably 40mesh for stars over half an inch.

Work small til you know lots about the hobby.

#8 Potassiumchlorate

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Posted 08 September 2012 - 03:30 AM

Oh, I sieve both parlon and red gum through 120 mesh screens before I mix them with anything else, but when mixing compositions I only use the 40 mesh screen. My potassium perchlorate is a bit coarse, so I mill it before using it. My strontium nitrate is a bit coarse and has some crystal water in it, so that is first heated in an oven for three hours and then milled for one hour.

Edited by Potassiumchlorate, 08 September 2012 - 03:30 AM.

"This salt, formerly called hyperoxymuriate of potassa, is used for sundry preparations, and especially for experimental fire-works." Dr. James Cutbush

Conflo, ergo sum

#9 MikeB

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Posted 08 September 2012 - 12:55 PM

Having to pass anything through a 120 mesh screen means you need to change your chemical supplier. Many substances do not screen easily and trying to work pounds through a fine screen is an exercise in futility. Pyro chems should already be finer than 100 mesh unless you knowingly purchase something with the intent of milling it down. A 60 mesh screen would be adequate in most cases.
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#10 psyco_1322

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Posted 08 September 2012 - 01:03 PM

I really like to screen most comps with a 30 mesh screen, 40 mesh is a little too fine for general mixing IMO. I do use a finer screen for screening my perchlorate to dust when making "fast" burning comps. The only thing that gets mixed through a 60 mesh screen is my whistle fuel, as it does need a very thorough incorporation. With 60 mesh, you really seem to have to push the material through, which I don't particularly like doing.

I've never had issues with red gum have chunks in it, but parlong does seem to have some larger pieces in it. I like to bind my stars with parlon so it gets dissolved anyway, and I've never had issues with rolling with the little bits still in there, as long as they pass 30 mesh.
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#11 Potassiumchlorate

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Posted 08 September 2012 - 01:57 PM

Do you roll by hand or do you use a machine? I find hand rolling with parlon very time-consuming.
"This salt, formerly called hyperoxymuriate of potassa, is used for sundry preparations, and especially for experimental fire-works." Dr. James Cutbush

Conflo, ergo sum

#12 worldcrafter

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Posted 10 January 2019 - 04:11 AM

just wondering if anyone uses a brush with nylon or brass bristles to push individual or mixed comps through finer mesh sieves? i would like to screen out some particulate from sulfur i recently bought, and it looks like i'm going to need 60 mesh or finer sieves to do the job.



#13 davidh

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Posted 10 January 2019 - 08:14 AM

I use these to push comps through screens: https://www.amazon.c...s=dough scraper

 

These are made of LDPE, and can be found in restaurant supply stores for around a dollar or less each.



#14 Nitrotitanite

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Posted 10 January 2019 - 11:34 AM

Bello is what my wife uses to make desserts.



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