9 replies to this topic

[tdpyro]

All of the aluminium and magnalium stars that we have been making recently have been swelling and cracking, and then start crumbling and turn powder given a long enough time.

I have been reading a skylighter article http://www.skylighte...cle.asp?Item=60 on the problems that can arise with fireflly stars. It indicates that a acidic potassium nitrate can cause crumbling problems, when used with aluminium. Is it possible that this also causes problems with magnalium based stars. (Our Potassium nitrate is GD)

Has anyone had any experience with these problems?
Does anyone know of a solution to this?

Using sodium bicarbonate seems to neutralise the acid and protects the stars from this effect to some extent, for example our D1 stars do not have this problem. But a similar based composition with higher amount of magnalium are starting to crumble. Using sodium bicarbonate induces a yellow colour , and causes the delayed glitter effect. On the skylight of article it suggests using potassium bicarbonate (this would not cause the yellow colour), does anyone know where this would be available from?

[karlfoxman]

All of the aluminium and magnalium stars that we have been making recently have been swelling and cracking, and then start crumbling and turn powder given a long enough time.

I have been reading a skylighter article http://www.skylighte...cle.asp?Item=60 on the problems that can arise with fireflly stars. It indicates that a acidic potassium nitrate can cause crumbling problems, when used with aluminium. Is it possible that this also causes problems with magnalium based stars. (Our Potassium nitrate is GD)

Has anyone had any experience with these problems?
Does anyone know of a solution to this?

Using sodium bicarbonate seems to neutralise the acid and protects the stars from this effect to some extent, for example our D1 stars do not have this problem. But a similar based composition with higher amount of magnalium are starting to crumble. Using sodium bicarbonate induces a yellow colour , and causes the delayed glitter effect. On the skylight of article it suggests using potassium bicarbonate (this would not cause the yellow colour), does anyone know where this would be available from?

Hmm just a quick thought, maybe thw swelling is being caused by gases from a reaction? Add 1-2 parts boric acid and see if it helps. Have not got time to reads the skylighter article so forgive me if its already in the formula.

[sasman]

I think i posted a similar problem i had with my own Home made maganlium...Cant remember if it was on here or passfire...But i had exact same problem ..

I made a few KG They rolled up perfectly round but when they started drying they all split like peas. Also when dry they didnt burn very well the Magnalium reacted with the Nitrate for sure.. I tried boric acid but that didnt make any difference . Tried drying thme in the oven.. tried not to get them to wet..all ways reacted.. so i assumed it was my homemade magnalium was to reactive?..

Since using some commercial magnalium the problem didnt happen on a small batch i made...

Ps.. The Formula was a simple willow mix with fairly coarse Magnalium 50/50 added about 10% i think ..When first mixed and burnt piles of it.. it made beautifull glittering crackling sparks...I just loved burning it!!.. it would look luverly in the sky.. Pitty it didnt work..

Edited by sasman, 16 November 2005 - 04:24 PM.

[tdpyro]

I was thinking that this might be the problem also, but when I made some brilliant white stars with -200 mesh magnalium did not suffer from this problem. Could it be a problem with the courser mesh magnalium?

[Draco_Americanus]

Maby try treating the magnalium with potasium dichromate, or linseed oil?

[Yugen-biki]

Treat the magnalium with linseed oil of parrafin. To be absolutely shure add +1% boric acid to the mix or solve the boric acid in the water you use to bind the stars.

[Richard H]

I wouldn't add boric acid to the composition, it will more than likely promote the attack of your Mg:Al. Instead try coating your Mg:Al with linseed oil and allowing it to dry before using in any composition.

[karlfoxman]

I wouldn't add boric acid to the composition, it will more than likely promote the attack of your Mg:Al. Instead try coating your Mg:Al with linseed oil and allowing it to dry before using in any composition.

Really, i never knew that Richard. Will make a note of that as its very handy to know.

Cheers

[Richard H]

While Mg:Al is more comparable to Aluminium in its reactivity than Magnesium, boric acid might still cause problems. It is a better approach to protect the metal by coating it.

Perhaps try coating, and a small amount of boric acid in your solvent when making the stars as an assistant buffer. Should hopefully stop the problem occurring.

[GBthriller]

Quickly, thank you for this thread, this forum, your wisdom and experience. You are helping me soooo much in this beloved art! *Then GB retreated to the shadows from wherest he came.*

*EDIT: Dec. 4 2005 Found myself here last, was looking for a solution to EXACTLY the same problem*

Edited by GBthriller, 04 December 2005 - 04:52 PM.