4 replies to this topic

[Bonny]

I'm currently rolling up a batch of Shimzu B-70:

Potassium Perchlorate 63.8
Parlon 13.8
Copper(II) Oxide, black 12.9
Red Gum 9.5
Dextrin 4

I plan on using some as cores for colour changing stars...probably TigerTail to blue for one. For the rest, what should I use as prime?
I will step prime if needed, but I was thinking either 'veline style' prime + a layer of meal, or trying a greenmix BP 'Universal prime' with Silicon and some Al.
Any suggestions?

Edited by Bonny, 26 June 2008 - 02:28 PM.

[BrightStar]

Any suggestions?

This blue will be fairly easy to ignite with most of the ordinary methods. If you are making just this batch then step prime it 50/50 with meal then a layer of green mix.

A 1mm layer of silicon prime will certainly ignite it if you are keen to experiment. Try a slightly under-oxidised meal (maybe 68% KNO3) made with fast willow or balsa and milled for only half an hour or so. Screen in 5% Si and bind with dex or gum arabic.

Edited by BrightStar, 27 June 2008 - 03:57 PM.

[maxman]

Why under oxidised brightstar?

[BrightStar]

Why under oxidised brightstar?

Simply because we want a mix that takes fire easily and burns hot but that also transfers some of this energy to the star. Ordinary meal tends to just flash off the surface. If you place a teaspoon of good meal on copier paper you should be able to ignite it without it burning through - clearly a hopeless prime... The under-oxidised and partially milled stuff lingers longer and burns much deeper.

The Si powder of course also helps a lot...

Edited by BrightStar, 27 June 2008 - 05:54 PM.

[maxman]

Ah fair enough, I take your point. Thats where i've been going wrong