BP binders

[ronmoper76]

Can i use phenolic resin in place of dextrin or red gum for BP. I was thinking it would act as a fuel perhaps? Maybe even speed it up? I thought i would ask before i attempted it to see what the general consensus was.

[justvisiting]

I wouldn't do it. The answers you get should always be in relation to the intended use for the powder, so you should always say what it's for, whether it be lift, burst, rocket propellant, match, etc... Phenolic resin seems to be a good binder for pumped stars that require very little (alcohol) moistening. I used it to roll stars and they skinned over and would not dry for weeks. Intuitively, it doesn't seem (to me) to be a good choice for a BP binder. Dextrin is commonly used for BP granulation, but it slows the powder down a lot at even 3%. At 5% dextrin though, BP mill dust is easily coated onto rice hulls for burst. The hulls could be further boosted if needed. When I made BP with my hot water method, I used CMC at 3%. It worked well for the mediocre powder it was used for. In pressed BP, potassium nitrate is the binder

[Bourbon]

Dextrin is commonly used for BP granulation, but it slows the powder down a lot at even 3%. At 5% dextrin though, BP mill dust is easily coated onto rice hulls for burst.

 

How does it work well at 5% on rice hulls if increasing the percentage of dextin slows it down? Does spreading the volume increase the flame-front and somehow equalize difference?

 

[justvisiting]

Bourbon, yes it certainly seems like a contradictory statement. I was relating personal experience. I'll guess at an explanation as best I can Granulated black powder variants are varying degrees of 'fluffy', or porous. I tested mediocre powder with baseballs, which had 3% dextrin as binder. 2% dextrin was also tested, but the grains of granulated powder were not robust enough, in my opinion. So I upped it to 3% and the difference was quite significant. With a hot powder made with a good BP charcoal, 3% might be just fine.

 

Considering rice hulls, I made those with hot BP mill dust. The hulls are pre-moistened by soaking them to saturation in hot water, and wringing them dry so that they don't drip. When the BP is coated onto them, it accretes very densely, as the water from the middle dissolves some nitrate and allows the powder to pack down. In my mind, I see it like rolling stars, compared to cutting them. I wonder if rolling BP has been done. I bet it would make some great lift for large shells.

 

I was just comparing a couple of scenarios as examples, since we are kind of blind on what the OP's powder is to be used for.

[Bourbon]

Sounds good. I was just making sure I wasn't missing something. Ive never coated hulls before.

 

So at 3%, it was still comparable to 5% coated hulls? Baseball testing... Hope I'm asking this correctly.

[justvisiting]

Sorry, I should have worded things better. I wasn't making any comparisons, I was just using 2 different, unrelated examples, to not make a point There was never a comparison because the baseball testing was done with the granulated powder, and the rice hulls were used as burst for 4" shells. Ned actually uses rice hulls for lift, and I think he did an article on it. I did it before, but there's a whole lot of sparks raining down from the hull embers- seems dirty to me. It wouldn't be hard to test rice hull burst with baseballs, but I haven't done it. I was kind of throwing stuff out there as examples, to show the OP the kind of considerations that come to mind with such a broad question, so we could narrow things down.

[ronmoper76]

I wouldn't do it. The answers you get should always be in relation to the intended use for the powder, so you should always say what it's for, whether it be lift, burst, rocket propellant, match, etc... Phenolic resin seems to be a good binder for pumped stars that require very little (alcohol) moistening. I used it to roll stars and they skinned over and would not dry for weeks. Intuitively, it doesn't seem (to me) to be a good choice for a BP binder. Dextrin is commonly used for BP granulation, but it slows the powder down a lot at even 3%. At 5% dextrin though, BP mill dust is easily coated onto rice hulls for burst. The hulls could be further boosted if needed. When I made BP with my hot water method, I used CMC at 3%. It worked well for the mediocre powder it was used for. In pressed BP, potassium nitrate is the binder

i like your thinking. i'm working on getting a die to make pucks soon.

[MadMat]

IMHO Using Phenolic resin for binding BP is a waste of money and it will more than likely slow the burn rate of the BP. I don't want to sound preachy but why do people continually try to reinvent the wheel with the process of making BP? There is a time tested way for making excellent BP. By time, I mean hundreds of years! First on order, you need a ball mill. Secondly, you press and corn it. OK, OK; granulating BP does work, but it doesnt pay to get exotic with the binder. For best results, you need something water activated and strong at very low concentrations. The red gum process touted by Sky Lighter is, plain and simple, crap. Stick with dextrin or CMC. Dextrin is cheap and you can even make it at home by baking corn starch. Other than for curiosity's sake, there is no real reason to try different binders.

Now if you want a die to make pucks, it is extremely simple and rather inexpensive to make. 1. get a piece of 2" sch40 or better yet (if you can find it) sch80 PVC pipe about 3-4 inches long. Sch 30 can be used but you will need to reinforce it with a couple hose clamps (stainless steel please). Make sure at least one end of the pipe is smooth, square and flat. 2. Get a quart of fiberglass resin ( it's even available in Wally World's automotive section) and a piece of fiberglass matting or cloth. 3. Cut up the fiberglass cloth/matting into small pieces. 4. Apply a thin coating of vaseline to the inside of the PVC pipe and place the smooth/ square end on a piece of wax paper or plastic wrap. 5. Mix up the resin according to the instructions on the can. 6 Pour a small amount of resin into the pipe and add a couple of pieces of fiberglass cloth. alternate resin and cloth. Attempt to keep the cloth pieces in the middle of your "piston" as much as possible and don't go overboard with how many you use. Try NOT to make any air bubbles, you may want to try saturating the cloth with resin before placing in the pipe and by all means pour the resin slowly. Add resin and cloth until it is about 2-3 inches thick. 7. Allow the piston to cure until hard. Repeat this process for a second piston. Allow the solvents in the resin to evaporate in open air at least overnight before using. The Pistons will shrink somewhat, but that is OK, because you DON'T want an airtight seal as you are pressing the BP. The larger and longer you make the pistons, the more they will shrink. If they shrink too much and the fit is simply too sloppy, you can wrap some turns of teflon plumbers tape near the business end of the piston, but remember you don't want to make the fit air tight!

Edited March 29, 2021 by MadMat