Sciencemadness Discussion Board

Ballistics gelatin - the real recipe - anyone here make their own?

RogueRose - 29-4-2018 at 14:00

A while ago I was into testing ballistics of a few guns I had and wanted to make my own ballistics gel, b/c I wasn't paying $250-400 for a large block. I had also made some gelatin based glue that used vinegar, glycerin, water and I think Isopropyl alcohol (not sure about the last one, it may have been in one recipe I made). What I ended up with was an extremely tough block of gelatin glue when I was done MUCH more resiliant and tough than the recipes of gelatin and water. I eventually made about 12 different recipes trying variations of amounts of the ingredients trying to figure out which compound gave different characteristics to the final product. I finally got a good recipe but I've seemed to misplace the work I did, though I may be able to find it if I look.

I just can't see that gelatin and water is much different than jello. My gelatin glue is anywhere form 50-300% more resilient to being torn which could be a good or bad thing, IDK. I just think flesh is more resilliant than jello.

Can anyone think of a reason why vinegar (5%) and glycerine would help make this mixture more resilient and sticky? The stuff was a rubbery solid at room temp but once heated to about 120-140 (depending upon recipe) it would turn into a liquid) but would then solidify into whatever container I placed it in.

I also found that it would mould after about 2 years (about 6-8 months if left uncovered, but only a very thin top layer that could be scraped off). I've heard that ballistics gel does this as well and can go rancid if not stored properly and it gets REALLY nasty.

Anyone have any experience with ballistics gel or with making gelatin based glues (mainly used for woods and such)? Any insight into this?

Fulmen - 29-4-2018 at 14:23

I have always used wet newspapers due to availability, I also think it's a more realistic medium than the standard BG. But this winter I tried a glycerin-based composition, and I'm very happy with it. It's 50% glycerin, 42% water, 8% gelatin (plus 0,5-1% sodium benzoate). It is much tougher than standard gelatin, shows little sign of drying out over time and seems to be infinitely reusable. I've stored a few kilos in the fridge for many months now without any mold.

RogueRose - 29-4-2018 at 19:39

Quote: Originally posted by Fulmen  
I have always used wet newspapers due to availability, I also think it's a more realistic medium than the standard BG. But this winter I tried a glycerin-based composition, and I'm very happy with it. It's 50% glycerin, 42% water, 8% gelatin (plus 0,5-1% sodium benzoate). It is much tougher than standard gelatin, shows little sign of drying out over time and seems to be infinitely reusable. I've stored a few kilos in the fridge for many months now without any mold.


That's an interesting idea but i don't think newpapers will work for what I want to do with tracking the impact trajectory like I can with ballistics gel. The 50% glycerin is an interesting idea where I used something about 3-5% and about the same of vinegar, maybe more like 5-8% vinegar. is the sodium benzonate to help keep bacteria down? When I talked about mold, this was on the glue I made and it was stored in a mason jar at room temp and I only noticed it at about 8 months on one jar that I had used a lot, and another jar that was sealed from the time I made it, only a little at 2 years.

I'll try making some small samples again and see what I can find out. I have to remember what the IPA was used for or if it may have been to put on the top layer of the glue once it congealed, to kill bacteria. I forget.

LearnedAmateur - 29-4-2018 at 21:48

I used to play around with gelatin mixtures when I was younger, not quite for real firearms but for airsoft guns and homemade projectile ‘toys’. I’d just use half the recommended amount of water for a jelly recipe so that it was still compressible and rubbery but didn’t bend much.

As for it going rancid, maybe have a play around with adding small percentages of ethanol or isopropanol? It should at least delay spoilage for a while but like with agar, gelatin is one of the most prime food sources for many microorganisms. Not sure how alcohols would interact chemically though, and how this would lead to altered physical properties, but I don’t think say 5-10% would have much of an impact.

Oh, and yes the sodium benzoate as a preservative helps to prevent spoilage. It would probably be a better option (as a non-volatile solid and used in smaller amounts) than what I mentioned in the above paragraph so it’s probably just best to disregard what I wrote there.

[Edited on 30-4-2018 by LearnedAmateur]

VSEPR_VOID - 30-4-2018 at 18:43

How realistic is it? Does it approximate human tissue?

LearnedAmateur - 30-4-2018 at 21:35

Probably not to be perfectly honest, I mean a 6mm plastic ball with less than 1J of energy could penetrate it.. It would’ve been a weaker version of BG so I’d say you’d need about 20-30% water (compared to jello) with some sort of crosslinking agent to make it harder, or even just that. A small amount of boric acid may serve useful here perhaps? Apparently it’s also used in urine samples as a preservative, so it could be dual use as well and keeps the mixture simple. I live in the UK so it’s not like I have a firearm to run some tests.

VSEPR_VOID - 30-4-2018 at 23:19

Quote: Originally posted by LearnedAmateur  
I live in the UK so it’s not like I have a firearm to run some tests.


*US Anthem Plays in Proud Response*

Are there any additives to make it flesh like? Maybe adding something that polymerizes might help, or large interlocking molecules, would help add rigidity

Fulmen - 1-5-2018 at 00:24

IIRC the standard 10% BG was formulated to mimic human tissue. Personally I've always felt it's too soft. Just stab a piece of raw meat with a blunt object, then do the same with BG. It's not even close. But density and viscosity might be right, and the most important criteria is that it produces consistent results. If penetration is 2x reality then just divide the results by 2.
The glycerin based recipe I use now feels much closer to reality, but that's just a personal opinion. I also like wet newspapers, but it generates a lot of waste.

LearnedAmateur - 1-5-2018 at 01:20

Like I mentioned, boric acid might make a good additive. You use it with PVA glue to make it into a slime via polymer crosslinking but I’m not sure how it behaves with gelatin, but crosslinking should add some extra strength since the gelatin polymers will theoretically hold together better.

Fulmen - 1-5-2018 at 01:50

That is an interesting idea, I might have to try it myself one of these days.

VSEPR_VOID - 1-5-2018 at 02:01

Quote: Originally posted by Fulmen  
IIRC the standard 10% BG was formulated to mimic human tissue. Personally I've always felt it's too soft. Just stab a piece of raw meat with a blunt object, then do the same with BG. It's not even close.


Muscle tissues are almost 'string' like. I bet that adding large amounts of fibers to the mixture might have the same effect.

Fulmen - 1-5-2018 at 02:59

The question is wether or not the bullet cares.

LearnedAmateur - 1-5-2018 at 03:41

I guess there’d be some way to do that, you might be able to get away with adding some paper pulp to the mix? Although if you want realism then you’d have to find some way to add fibres in parallel (as opposed to random orientation) then potentially bind them with gelatin. Some cool ideas to try out in any case, I bet they’ll be useful.

VSEPR_VOID - 1-5-2018 at 09:24

Yarn would work