Drying 20mm Lancaster silver

[Potassiumchlorate]

How long would you estimate that it takes at 20^oC and 50% relative air humidity, if they are pumped and contain +12% alcohol/water?

[pyrojig]

How long would you estimate that it takes at 20^oC and 50% relative air humidity, if they are pumped and contain +12% alcohol/water?

 

Probably a few days. Id suggest using a fan to circulate the air . Aluminized stars seem to dry fairly fast for some reason in my experience.

 

I prefer to break a star open to expose the core , then scratch it with a fingernail to see if it is dry. This is a good way as well to find out if high charcoal stars are dry, or of the are driven in. Ive saved batches of driven in stars by forced drying in a dehydrator , when it went that way.

Edited February 9, 2012 by pyrojig

[Mumbles]

I might put it closer to a week with good air circulation. Just keep them on a tray and let them dry until they stay constant for 2-3 days in a row.

[Potassiumchlorate]

Thanks, guys.

[Potassiumchlorate]

They seem to be almost dry by now, though I can still scratch them a bit with my fingenails but not crush them with my bare hands.

[Potassiumchlorate]

They seem dry now.

 

What should I prime them with? Last time I used thermite in NC-lacquer, but would pinball prime with silicon do? They're in principle chlorate flash with an addition of slower aluminium and a binder. I like them a lot, though. Relatively cheap and easy to make.

[pyrojig]

The pinball prime sounds like a winner.

When testing to see if the stars are dry , using your fingernail.... I look to see if the comp is soft, or can be scored. If it leaves a light colored scratch mark w/o gouging the star ,then usually it is dry.I have had charcoal stars ,when driven-in that could not be crushed, but the core was wet still. At that point the only thing to do is force dry them. This is why I stress breaking a star open to see if it is driven-in.

Edited February 21, 2012 by pyrojig

[Mumbles]

I've never made this particular formula, but others I've had good success with lighting with just BP. If that does it, the pinball prime should definitely do it, you may not even need the silicon. At least there is no such thing as too much on fire when it comes to stars. Remember, pinball is not a set it and forget it prime. It generally should have a layer of BP over the top to ensure everything lights.

[mabuse00]

I made a batch of Lancaster Silver last year, dextrine bound and much to wet, so I got some ugly lumps.

 

In a weak confined rocket header they lit all just from the H3 break.

 

I was not very happy with them, the lumps were huge but they burned extremely fast. More like short white flashes, despite their size.

I lit one lump on the ground with visco and went 3 meters away, but this thing got airborne like a go-getter, hit my arm and made an nice hole in my pullover.

 

 

I used 325mesh stearine coated aluminium bright only. The formula even calls for a part dark aluminium, imho crazy.

I would rather suggest to use a large part of atomized aluminium...

Just my 2 cents.

Edited February 21, 2012 by mabuse00

[Potassiumchlorate]

I used atomized the last time. Then they burned far too slow, although the effect was very nice.

 

The composition is:

 

Potassium chlorate 56

German Black 19

Bright Al 19

Dextrin 6

 

They burn within a second using this comp.

[Potassiumchlorate]

*Bump*

 

I might just burn the old ones on the ground. I made new ones with SGRS instead. Considerably harder. It's still hard to consolidate them, though. I don't know what I'm doing wrong.

[mabuse00]

It's still hard to consolidate them, though. I don't know what I'm doing wrong.

I made another little batch too, this time with PVB, and I'm having the same problems.

 

I'm sure the stearine cover on the bright aluminium is to blame.

 

When one of them was shot from a stargun, the star disintegrated at the muzzle and made a report like an flashbang. Miraculously the thin paper stargun survived.

 

That bright aluminium is a pita. I will only use it for reports in future.

[Algenco]

stearine is definitly the problem, you'll need to add alcohol to disolve it.

I have some bright flake with a heavy stearine coating that's a pain to use

[Potassiumchlorate]

Hm, too bad, because the effect is very beautiful, and they ignite almost by just looking at them.

[Algenco]

use 75/25 water/alc to bind, should work fine

I like making comps with bright flake, cheap and looks great.

I bought a bunch @ $2lb

[Potassiumchlorate]

Nah, I had alcohol in it when I used dextrin. The stars are much harder now.

[Mumbles]

A little alcohol is almost required in my experience to break the surface tension. I've made silver soups on multiple occasions trying to wet it with just water and way over doing it. As soon as a drop of alcohol hits it, it's a slurry and I need to mix up 3x as much comp just to soak it up.

 

One traditional method to bind silver stars is to use thin wheat paste as the wetting agent in addition to the binder in the composition. Often a little alcohol still helps here, though it will wet the aluminum eventually I've found. I use about 6:1 paste:water for pasting shells, and around 10 or 12:1 for wetting comets. Later on in Lancaster's book, Shimizu talks about silver stars too. He mentions that pressed stars should have around 5% SGRS, and round stars 8-10%. It's not clear to me if he's adding the SGRS as a powder, or as a prepared slurry.

[Potassiumchlorate]

How much alcohol can you use before the SGRS starts to getting destroyed? It's obvious that 25% will be way too much.

 

I actually had that bowl with silver star composition and water standing outside for almost a month to break the surface tension!

[Mumbles]

I don't use anywhere near 25% even with dextrin. I literally add a quick splash of alcohol to anything I'm working with. It's maybe a couple percent at most. I don't premix, just wet with some water and add a little bit of alcohol to the bowl.

[Potassiumchlorate]

Do you think 5% alcohol would be good and not destroying the SGRS? I'd love to use it for rolling.

[AirCowPeacock]

It was my understanding that the solubility of Dextrin and SGRS becomes less and less as the alcohol content goes up. If you were to make an aqueous solution of SGRS and add (alot of) alcohol the SGRS would just percipitate out.

[Potassiumchlorate]

Dextrin can stand a lot of alcohol. SGRS can stand considerably less.

[Potassiumchlorate]

I tested the old dextrin bound stars in a 6" shell today. Stars+burst weighed about 825 grams. Burst was H3 on cotton seeds, 1:1. The whole shell weighed about 1100 grams. Lift was 75 grams of BP.

 

The shell started to drop just a little bit before the burst, so the next time I will either make the time fuse a few mm shorter or increase the lift with a few grams.

 

I'm sorry for the shaky filming. I was doing it all myself and the place is a kind of swamp

Edited November 26, 2012 by Potassiumchlorate

[BJV]

One Question, why did you shoot your shell in the daylight. Can't see much............

BJV

[Potassiumchlorate]

I wanted to test my new BP (again) as well. I find it easier to estimate the height and to see whether the shell drops or not before the burst

 

It will of course look a lot better at night

Edited November 26, 2012 by Potassiumchlorate