No Dextrin....Substutite?

[Ryanjax]

I would like to pump some tiger tail stars, but I have no dextrin. Is there any product that I can use in the place of dextrin until i receive mine?

[Bananaphone69]

Well, you could use corn starch... But you would have to heat it in an oven on 400 degrees for about 4 hours spread over a cookie sheet if you use a whole box... But I guess I just described how to make dextrin...

[dagabu]

Well, you could use corn starch... But you would have to heat it in an oven on 400 degrees for about 4 hours spread over a cookie sheet if you use a whole box... But I guess I just described how to make dextrin...

 

Uh, just make sure you stir it all of the time, it takes about.001 seconds for it to start burning and its a mess if it does that. I make mine in the oven, takes about 2 hours to make, smells like marshmallows, wait till it turns a pale yellow and take it off the heat.

[andyboy]

Wallpaper glue, look it up on the package so it says CMC (Sodium Carboxymethyl Cellulose) and use at a ratio of 1-3%.

 

 

Edit: make sure you don't over-wet the mix, it will be like bubble-gum and you won't be able to press it when using CMC.

Edited July 21, 2009 by andyboy

[dagabu]

Wallpaper glue, look it up on the package so it says CMC (Sodium Carboxymethyl Cellulose) and use at a ratio of 1-3%.

 

 

Edit: make sure you don't over-wet the mix, it will be like bubble-gum and you won't be able to press it when using CMC.

 

Cool! I just got done hanging some paper, have to see if it works.

[shagaKahn]

As I've never made tiger tail stars I ain't sure if the dextrin represents a source of fuel or is only a binder.

 

If binder, then I've used ordinary fabric starch with great effect for binding stars. (Comes in a big jug--NOT the spray kind).

[NightHawkInLight]

Easy. Liquid laundry starch just as shagakahn mentioned. It dries faster and much harder than dextrin. It's all I ever use to bind stars anymore. Unless they cannot be bound with water that is. Often I will dilute the starch 50/50 with water.

[Seymour]

Other alternatives include Gum Arabic, SGRS, CMC, Guar gum....

 

And wheat paste.

 

Adding flour to water, stirring and heating until thick will produce a paste that is perfect for pasting shells, and quite effective (if rarely used) for binding stars. Because it is a paste, you knead it in to the composition before pumping.

[Pretty green flame]

On the subject of SGRS, this stuff is overrated in my opinion. The stars are somewhat stronger than dextrine but not much difference when cutting, a MAJOR downside of SGRS is the drying time. I've had 10mm pumped stars dry for over 10days, with dextrine they were dry within 3-4days. And above all I've had this stuff decrease the burn rate of some of my stars and ruin their effect. The only good thing i've noticed with SGRS is the fact that it it is more sticky than dextrine, which helps with priming things and coating rice hulls with BP.

[Seymour]

It is often said to be superior for colour changing stars, because it is more effective at preventing diffusion of things between layers.

 

Possibly related to your experience, as it takes longer for water to diffuse out!

 

I'd have thought that if it took so long to dry, the time that it allowed for diffusion would have overcome the slower rate of the phenomenon...

Edited July 23, 2009 by Seymour

[FREAKYDUTCHMEN]

Hmmm, where did you get your sgrs from PGF?

Most of my rolled stars dry in 1 or 2 days (not forced) and sgrs is less stickier than dextrin IMO.

Most compositions only need about 2 or 3% sgrs for binding.

 

If you like to roll big stars, 15mm and bigger, sgrs is a better option then dex because the star doens't get wet in the centre when rolling a new layer on the star.

[Pretty green flame]

Most of my rolled stars dry in 1 or 2 days (not forced) and sgrs is less stickier than dextrin IMO.

Most compositions only need about 2 or 3% sgrs for binding.

 

If you like to roll big stars, 15mm and bigger, sgrs is a better option then dex because the star doens't get wet in the centre when rolling a new layer on the star.

 

Could be the fact that i've substituted 1:1 SGRS for Dex. You are right about the water resistant characteristics of SGRS, it's way superior to dextrin in that aspect.

[FREAKYDUTCHMEN]

hmmm now I'm thinking about it I've had one experience with cutting with sgrs and yes that wasn't a good one. But I don't like cutting anyway hehe.

Trying to wash of some sgrs bound composition on your spoon or something is pretty difficult yes hehe.

Edited July 23, 2009 by FREAKYDUTCHMEN

[Swede]

I like the laundry starch concept. A can of spray starch might work well for priming stars... give them a blast, add prime, roll about a bit.

 

I am not a fan of Dextrin or SGRS or Gum Arabic. CMC gum I'm still getting used to. I prefer binders that use non-aqueous solvents, like Red Gum. We use all these plant-derived, traditional binders that have existed for centuries, when there are so many other modern substances that can function the same way. There are hundreds of glues that might work better, dry faster, than dextrin. But the traditional recipes call for Dextrin or SGRS, so we use it. Wheat paste for shells - there's got to be something modern that functions better, that doesn't take days to dry.

 

I guess what I'm trying to say, are we slaves to tradition? Or is it more a case of "It works, why mess with it?"

[FREAKYDUTCHMEN]

Dextrin and phenolic resin are binders which are used nowadays in most Chinese and Spanish firework factories. Dextrin with water(/Alc) and phenolic resin with only alc.

I don't see a reason why sgrs and dextrin shouldn't be used, sgrs is a bit more expencive than dextrin so that's the reason why most firework factories prefer dextrin above sgrs.

Red gum isn't in any composition a binder, only a fuel.

[Pretty green flame]

Swede, I don't think we're slaves to tradition, most people chose to use dextrin or plant derived binders because they're cheap and easy to use. I for example don't feel like messing around with non-aqueos binders because they're a pain to clean up. And in some cases it probably is the "If it works, why mess with it", for example, I swear by simple wheat paste for binding stars with a lot of greasy aluminium in them. Why? Because it cheap and is one of the strongest binders i've tried out yet. In the past i've even tried gelatin for binding cut stars which worked wonderfully. Another exotic thing is I belive fiberglass resin, there was a short article about it's use on rec.pyro a couple years ago, though i belive it was said that it dramatically reduced ignitability of the composition.

[Arthur]

Traditional binders are cheap and vegetable in origin Red gum, shellac, SGRS, Dextrin, Gum Copal, Gum Arabic and so on

 

Usually they are cheap and easy to use. Usually they are safe touse in pyro compounds, or their incompatibilities are known and avoidable.

 

Modern resins are very usable but not fully understood from a pyro perspective!

 

I am aware of stars being pumped in a press using 10% resourcinol resin initially mixed with acetone. Produces rock hard stars in 2 hours at 22C permanently bonds tooling -there is NO solvent. and makes stars that can be washed and still burn! Just don't add the resin, substitute it for some of the fuel.

 

Polyester resin may well work, but trying to incorporate it at 5 - 10% is too hard usually it only works at bigger binder content and then the comp goes very slowly. Now, perhaps if you dissolve it in styrene it will blend in, then lose surplus styrene, then harden.

 

With needs of expensive binders and solvents and the risk of harming the tools resin binders are more expensive than trad binders, but produce a waterproof cop ready to fire in less than a day even for thick sections. A 3" comet can be ready to fire in an hour in warm conditions, and they are cured through unlike trad binders that risk the core of a big comet being damp long after the outside is hard.

[Mumbles]

You guys have odd experiences with SGRS. It has the elasticity property that dextrin does not. This makes it usable/ideal for the toro rolling process where a star comp slurry is used instead of just solvent to wet the stars.

 

In my experience with both, SGRS dries faster, is stickier, and produces harder stars than Dextrin. I like it a lot better for cutting actually. It is kind of rubbery, and makes the stars more resilient to crumbling when not completely dry. One thing I don't like about it is how long it takes to activate by water, which many will agree is significantly longer than dextrin. For this reason I don't use it to coat hulls. If you don't have a star roller, it's a pain in the ass to sit there and stir everything until the binder finally activates in each addition of composition. This makes it tiring to work into composition for cutting stars too. My comets turn out rubbery and flow a bit if I use it in them though. Multiple pressings don't like to congeal either. I use SGRS for cutting, and dextrin for pretty much everything else.

 

I must admit though, properly made good dextrin (not the stuff from the oven), really is amazing stuff. This will rival the hardness of SGRS.

[NightHawkInLight]

Swede, I don't think we're slaves to tradition, most people chose to use dextrin or plant derived binders because they're cheap and easy to use. I for example don't feel like messing around with non-aqueos binders because they're a pain to clean up. And in some cases it probably is the "If it works, why mess with it", for example, I swear by simple wheat paste for binding stars with a lot of greasy aluminium in them. Why? Because it cheap and is one of the strongest binders i've tried out yet. In the past i've even tried gelatin for binding cut stars which worked wonderfully. Another exotic thing is I belive fiberglass resin, there was a short article about it's use on rec.pyro a couple years ago, though i belive it was said that it dramatically reduced ignitability of the composition.

Fiberglass resin is just your usual epoxy as far as I'm aware. I've used various epoxy's as a binder and fuel in various nitrate based rocket comps. A guy that I lost contact with about a year ago went much more in depth with it than me. He even used NaNO3 and NaClO3 as the oxidizers for several very successful and brilliantly colored rockets. The epoxy did a great job of sealing it away from any pesky moisture in the air. The absurdly hard fuel grain from my experimentation hardly requires a casing to confine a cored rocket. The grain itself holds much of the pressure. Price is the issue with epoxy usually being over $30 a gallon. I'm yet to try it as a binder in stars.

[laser200]

I make my dextrin out of corn starch too but only bake for about 1 1/2 hours...