33 replies to this topic

[Arthur Brown]

Anyone care to share a formulation and method for "Slow Gold" stars, Who developed the formula, and what provenance do you have?

[starseeker]

Anyone care to share a formulation and method for "Slow Gold" stars, Who developed the formula, and what provenance do you have?

I was going to ask for the formula myself arthur,it is a lovely effect.

[digger]

I was going to ask for the formula myself arthur,it is a lovely effect.

Give me a mo and I will post details of how I do it. I am sure you are referring to a shell or two you may have recently seen.

[BrightStar]

Slow Gold is credited to Dave Buell and is formulated as follows:

Potassium Nitrate: 36
Charcoal Airfloat: 29
Charcoal, 80 mesh: 14
Sulfur: 9
Titanium, sponge, 40-80 mesh: 7
Dextrin: 5

It's essentially a slow burning charcoal willow star with added Ti to give a bright brocade effect. To prepare, mill the ingredients, except the 80 mesh charcoal and Ti, together for a few hours and then screen in the remainder. Use a moderately reactive charcoal such as pine.

An 18mm pumped star will burn for 10+ seconds and hang for 30s or so in the sky. A beautiful effect indeed...

Edited by BrightStar, 28 April 2009 - 08:43 PM.

[digger]

Here you go (Yep Buell)

Potassium Nitrate 36
Charcoal Airfloat 29 (Pine)
Sulfur 9
above 3 milled together for 1 hour ish

Charcoal, 40 - 80 mesh 14 (White Pine)
Titanium, sponge, 20 mesh 3.5
Titanium sponge, 40 mesh 3.5
Dextrin or SGRS 5

I find that a coarser grade of Ti gives a better effect with much longer hanging white sparks. The type of charcoal also has a bearing on the effect.

In the shells at the weekend the stars were 22mm pumped, 30mm long. The stars break up in flight to give the effect. 10 seconds sounds a little long for the flight, but the hang time can easily be 30 seconds as you say Brightstar.

Edited by digger, 28 April 2009 - 08:39 PM.

[BrightStar]

In the shells at the weekend the stars were 22mm pumped, 30mm long.

This one perhaps?

changing-peony-and-slow-gold.avi

Edited by BrightStar, 28 April 2009 - 09:11 PM.

[digger]

This one perhaps?

changing-peony-and-slow-gold.avi

That is a lovely shell, I believe that belongs to another Forum member. If he wants to own up.

Here is another slow gold from the day, unfortunately less well filmed as it was a little lower on the break.Clicky

[AdmiralDonSnider]

Slow gold really is a gem - as most brocade formulas are.

I just wonder if ball milling is necessary to achieve the long hang effect and the dense tail; or could you just use airfloat charcoal?
Another possibility could be wet processing (precipitation) - Shimizu rates wet methods very high for charcoal and willow effects.

Edited by AdmiralDonSnider, 01 July 2009 - 08:17 PM.

[Mumbles]

When I made it, I simply screened the chemicals, and used commercial charcoal for everything. It worked fine. I made 3/4" to 7/8" stars, and they burned fairly well. I'd say maybe 6 or 7 second burn time with a hangtime probably approaching a minute. I replaced half of the Titanium with coarse flitter Al, which added to the long delay.

[seymour]

I on the other hand ball milled the ball-millables, and had to add some Sodium bicarbonate to get it to burn as slow as desired.

I'm sure my charcoal contributed though, my pine is fairly fast.

[Pretty green flames]

Any adverse effects on the performance of these stars when they are cut? I don't want to scratch my tooling to death when making these as I hear titanium is pretty rough on tooling.

[digger]

Any adverse effects on the performance of these stars when they are cut? I don't want to scratch my tooling to death when making these as I hear titanium is pretty rough on tooling.

It sure is. Although it depends on the type of Ti. I find that sponge is not to bad with stainless steel or bronze tooling. However turnings destroy everything.

[cooperman435]

Ill second that. Stainless steel pump was scratched to buggery after doing a load with turnings in. Polished up again later but I wasnt pleased!

[Arthur Brown]

Plastic disposible syringes from ebay can be turned into pumps! Trouble is that there seems to be no standard relationship between volume and diameter.

Pump stars then discard the pump when too worn.

[AdmiralDonSnider]

What about rolling Slow Gold stars? I know that such brocade willow formulas are usually made into rolled stars for our beloved jap shells, but isn´t the coarse titanium (or FeTi in other formulas) really tricky to roll?

The comp isn´t expected to work well pumped and cut either...

Edited by AdmiralDonSnider, 13 March 2010 - 06:51 PM.