Crossettes shattering out of star gun?

[MasterBlaster]

Hi all I have been trying to make crossettes for a while now. I finally bought a real crossette pump and thought that it would solve my problems but now every one of them shatters on its way out of the star gun. I am using Win 26 and Long Hangtime Yellow comps. Ive been wrapping them in paper, with 1 or 2 turns of gummed tape after that.

 

Both comps work great out of the gun as regular pumped stars, its just the crossettes that are breaking. Also Ive tried them in two tube sizes on my gun, they're half inch stars and one tube fits with about 1/32" all around, the other fits with about 1/16" around the star. Both tubes shatter that stars.

 

Any ideas would be great,

thanks

[lloyd]

Blaster, I think they're cracking.

 

 

How are you drying them? If there's no aluminum or Mg/Al to react wet, then dry the comets as slowly as possible.

 

Crossettes tend to crack, because the thinner sections dry (and thus shrink) so much faster than the thick sections. In order to prevent that, slow the drying so that everything shrinks at the same rate.

 

Lloyd

Edited February 4, 2017 by lloyd

[MasterBlaster]

Ok thanks a lot lloyd ill give it a try

[MrB]

Cracking due to drying to fast, would this possibly be countered with a lower solvent content (and, if needed higher pressure) when making the crossette?

 

Guess it sort of comes down to if you are making these by hand, or with a press, and what the current solvent % is.

[lloyd]

Indeed, Mr. B. I press all my crossettes at between 4-6% moisture. (and for that very reason)

 

Lloyd

[MasterBlaster]

Now that you say that MrB, I usually use an arbor press when pumping my stars but my new pump doesn't fit under the press so I've been pumping by hand. With the press I use as little moisture as I can get away with so since switching to pumping by hand I'm probably not getting enough pressure. Just another reason for me to get/make a real pyro press!

[OldMarine]

MB, what size crossettes are you pumping? If they're under 1-1/2" I'd ram them with a mallet rather than just hand pumping them. I don't know what is in the yellow comp but the Glitter should ram well.

[MasterBlaster]

Yeah OM they're half inch so they're quite small. I'll give that a try too.

 

So I just started experimenting with some potassium chlorate comps, I figure I'll stick with potassium for a while and go from there once I get a feel for it. But when pumping chlorates can they be rammed with a mallet, or are they too sensitive for that? Or does it just depend on the formula? I know to stay away from sulfur, but I've also been wondering is the minute amount of sulfur that may be left behind after washing my pump enough to sensitize a chlorate comp?

[OldMarine]

I don't know much about chlorate comps but I don't think I'd ram them with a mallet. A simple washing with soap and water should take sulfur off your pump.

[lloyd]

Blaster, until you 'Master' them with BP comps, you're not going to have the feel for the variables you need to handle color comps.

 

I've (personally) pressed hundreds of thousands of crossettes, small and large (commercially). I always had trouble with larger color comp crossettes cracking.

 

I know yours are small, but still... start with the basic stuff, and work your way up.

 

Lloyd

[OldMarine]

I'm hooked on phenolic resin bound comets. I just wish it didn't screw up glitter comps because it makes for a very hard comet.

[MasterBlaster]

Ok sounds good thanks guys,

 

I keep reading about phenolic resin here on the forum, it sounds really nice to work with

[schroedinger]

Blaster, forget about phenolic resin for now, you need to get the basics right.

 

You should start with C6 or C8 comp.

 

These can be rammed or pressed on an Arbor press.

 

Also use 7% dextrine instead of 5% for crossetes and dry slow in the shade. If you got those working it is a lot easier to go over into other comps, but charcoal comps are best for learning and show errors quite good.

 

Phenolic also is more common used for cross binding with hexamine . wich requires heat or in higher ratios with alcohol giving quite poor results in comparsion to other binders. For pumping try to stay with water when ever possible, working with ollatile solvents is a lot of pain, since you get comp sticking everywhere in your pump, ruining the stars or needing a lot of cleanup Also alcohol likes to go between the sleeve and plunger, evaporate and leave binder behind and get your plunger stuck.

[MasterBlaster]

Haha that's good to know about using volatile solvents in a pump, I just ordered some phenolic today and while I wasn't planning on using it for crossettes right away I certainly would have learned that the hard way.

 

Ill post how it goes when I make a new batch, It'll be a week or two though, my new project is converting my arbor press into a rocket press based on the guide at skylighter so I can get more height out of it, and press my crossettes.

[Livingston]

Sometimes if your pressing to hard you can get cracking in your comets.

[OldMarine]

The only comps I've had trouble with using phen/hex binding in are glitters because it slows the effect. I can press an 1-1/2" BP/Ti/Crackle comet and place it in my food dehydrator at 160°F for about 2 hours and then go put it in the air. It's as hard as a billiard ball.

Edited February 9, 2017 by OldMarine

[dynomike1]

The only problem that i have had with crosets is if they have a crack in them right out of the pump. I think i have been using 5% Dextrin. That is pressing or ramming, i also stay away from Chloride comps.( Perchlorate only). Om if you think phenolic messes up glitter try it with strobes. Now if you want a really white bright star try Blessers white strobe with phenolic. I dont know what y'all are doing, or what i am doing wrong, but phenolic gives me a headache sticking to everything, but i do like pumpin stars with it. I am going out on a limb here. MB are you letting the stars dry real good before wrapping them? After pumping crosets i forget about them for a couple of weeks before wrapping. Check each one for cracks when it comes out of the pump. I mean even a hairline crack.

[OldMarine]

I haven't tried any strobe stars yet but have been playing with the phen/hex bound colors and have had no problems with the comp sticking to anything. Maybe reduce your alcohol a bit?

[MasterBlaster]

dyno, I think my problem was that I didnt have enough pressure. I had just gotten a new pump that didnt fit under my arbor press, so I was pressing by had without upping the moisture enough. Either that or I was drying them too fast and they were cracking that way. I didn't notice any cracks when I pumped them, but ill admit I wasn't looking for them at the time so ill keep that in mind next time.

 

OM, I keep reading that heat is required when working with phenolic/hexamine. When you put your comet in the dehydrator at 160, is that all that's requred to heat it? or do you have to add heat elsewhere in the process?

[OldMarine]

No, the 160° is plenty to cure the resin with the hex. In 2 hours consumer sized comets clink like pool balls when tapped with a spoon!

[MasterBlaster]

haha damn that's impressive, my phenolic arrives tuesday! I'm chomping at the bit to give it a try

[Mumbles]

Are you getting the phenolic from Jim Widmann/ctpyro.com/pyrocookbook? There are probably other good sources too. That is supposed to the be good stuff. Not all phenolic is created equally.

[MasterBlaster]

I ordered it from fireworkscookbook, hopefully its good I'll do my best to report how it works out for me if no one else has tried theirs.

[Mumbles]

It's the same stuff Jim sells, and should work great.

[Mia]

Well ever thought about PVB?