Burn rates

[Merlin]

Is there any data or charts that categorize the relative burn rates of established star formulas as fast or slow?

[Carbon796]

I don't believe so. Though usually if the formula is from a known/published source. If it is particularly slower or faster than " average " it will usually be noted.

[Carbon796]

Merlin, you better hope that rockncards guy isn't over here. Your going to give that guy an aneurysm

[Merlin]

Who is rockncards? I don't mean to be pesty. I am a reloader and burn rates for various powders are established. Just wondering. Someone said D1 is slow burning. It would seem it would be relatively useful to have an idea of burn rates in order to approximate the pin/fuse depth on crossettes or to determine star sizes in shells. I have searched but nada. As you say it is either mentioned in the formula or you have to learn from experience.

[lloyd]

Merlin,

I didn't intend to say that it's 'slow burning', only considerably slower than the comp I was employing in my crossettes. Our formulae were mostly Commercial Meal-D, except for the 'color comps', which were enhanced in burn rate with Mg/Al.

 

To our tastes, crossettes should have well-defined, nearly-horizontal branches, when they're working correctly.

 

D1 tends to 'droop'. To some, that's a desirable feature.

 

But... in answer to your question -- I don't remember any well-done review of the relative burn rates of different compositions. Most guys just press a 'square' comet, and test its rate (hopefully recording the burn time) in order to compare a comp's rate vs. others they've used.

 

We did have such a table, but since my previous employer is still using those same formulae, it's still proprietary. Sorry.

 

Lloyd

Edited May 20, 2017 by lloyd

[Carbon796]

Nope, not at all Merlin.

[Merlin]

Merlin,

I didn't intend to say that it's 'slow burning', only considerably slower than the comp I was employing in my crossettes. Our formulae were mostly Commercial Meal-D, except for the 'color comps', which were enhanced in burn rate with Mg/Al.

 

To our tastes, crossettes should have well-defined, nearly-horizontal branches, when they're working correctly.

 

D1 tends to 'droop'. To some, that's a desirable feature.

 

But... in answer to your question -- I don't remember any well-done review of the relative burn rates of different compositions. Most guys just press a 'square' comet, and test its rate (hopefully recording the burn time) in order to compare a comp's rate vs. others they've used.

 

We did have such a table, but since my previous employer is still using those same formulae, it's still proprietary. Sorry.

 

Lloyd[/quote

Thanks. I will come clean and at the risk of appearing stupid say that what I plan to try once I get the timing down is a glitter comp above the nipple and electric green below. I'm thinking a color going up and it breaks into a glitter.

Edited May 20, 2017 by Merlin

[MondoMage]

Thanks. I will come clean and at the risk of appearing stupid say that what I plan to try once I get the timing down is a glitter comp above the nipple and electric green below. I'm thinking a color going up and it breaks into a glitter.

 

I don't know if I've ever seen a crossette that went up as a color star/comet only to break as glitter. It would a very pretty effect, I think.

[lloyd]

I think it would be very pretty, also. But I recommend AGAINST trying to press it as a unit.

 

Press a green comet of the desired thickness for the lift time you wish. Press a crossette with the tit-hole exactly flush with the bottom surface (as close as you can get without damaging the tip). Dry both (completely). Then mate them with a generous application of glue of your choice (I suggest carpenter's white glue, and NOT 'Elmers', which is now shy on binder), and dry that whole assembly.

 

Then 'treat' any holes in the margin of the joint with a bit more white glue, and when that's dried, fill, cap paste, etc. as you would a normal crossette.

 

You're not likely to get the same shrinkage rate between the glitter and the green, and they will almost inevitably break apart while drying. It's better to press them individually, then join them after a full and complete drying cycle.

 

BTDT. We made color-changing crossettes, also. All were made by the above methods, after many failures trying to press them as a unit.

 

This was recently discussed in another thread about pressing combination color/glitter or color/silver pillbox stars...although I cannot remember if it was here or on another forum. Some of the 'experts' like Mike Swisher agreed that it was not productive to try to press the color and BP comp in one pressing, but to join the comets after drying.

 

Lloyd

[Merlin]

Lloyd. Now that is what I call valuable info! I have to try it. The area around the pass fire will have to be clean of glue. May try to open the fuse hole enough to get more than one strand of fuse in. I would have used nitro cellulose to glue the halves good you specified the glue. Thanks again. I will post if I'm able to pull it off.

[lloyd]

I'd recommend gluing them together without regard to any glue contamination, then take a small drill bit and just 'clean out' the tit hole until you JUST touch the color layer, but no deeper. Because the comps will be so different in color, it will be easy to see when you penetrate.

 

Lloyd