I just got some Nitric acid and am wanting to make some flash paper, but I've looked everywere for the proper acid ratios but can't find anything other than warning not to make your own, and crapbook pages.
I searched the archive and found a post by alchemist stateing to use 4 parts H2S04 and 5 parts NH03. And BTW is powerlabs down or is it just my computer? And does anyone have a copy of the? because it list on there site that issue has a forumal for flash paper.

Journal of Chemical Education
December 1995 Vol.72 No.12

isn't it just NC using paper as the cellulose source?

Ya, but I think there it a special ratio of acids for flash paper so that it burns differntly than plan NC. Or I could be wrong.

Powerlabs is going up and down recently, I think it's server troubles.

Try the backups: <a href="http://web.archive.org/web/*/http://www.powerlabs.org" target="_blank">http://web.archive.org/web/*/http://www.powerlabs.org</a>

Sam Barro's ratios for NC are as follows.

2.5ml 98% H2SO4
2.5ml 70% HNO3
.5gm Cellulose

This is done with no ice bath. Cellulose was left in bath for 5 minutes.

I'll just C&P for the Hexanitrocellulose synth so there's no missing info.

(For curiosity purposes only, POWERLABS outlines the method used for making rocket-fuel and double base powder grade nitrocellulose.)
The procedure is very similar to the one outlined above, except it uses a slightly different nitrating mixture. The proportions are now 35% / 65% (by volume) for HNO3 / H2SO4, assuming that the acid concentrations used were the same as the ones used above. 5 parts of acid are used for every part of dry cellulose (per weight). An alternate nitrating mix is made by adding 1gram of finely powdered Potassium or Sodium Nitrate (KNO3/NaNo3) for every 3.325g (3.819ml) of cold concentrated Sulphuric Acid (H2SO4), and than add cotton to this nitrating mixture when the temperature has stabilized. I don't use this particular procedure because it is hazardous (there is a lot of heat involved in the formation of nitric acid by removal of nitrate from the potassium ion) and can cause sputtering as well as releasing toxic fumes. Plus resultant mixture is not only nitric and sulphuric acids, but also includes potassium or sodium sulphate, which will have a negative effect on the quality of the final product.
Complete nitration takes about 10 minutes at room temperature. On a small scale not enough heat is evolved to justify an ice bath, which would only slow the process down. The mixture with a greater sulphuric acid content is able to impart more nitrate ions to the cellulose, causing it to have a much higher nitrate (nitrogen and oxygen) content. The procedure is still reasonably safe to perform from a stability point of view (meaning that it is virtually impossible for the nitrocellulose to form upon formation), but now the resultant product (when dry) burns a lot faster, hotter, and releases much more energy than the trinitrate above. It is, in fact, one of the most energetic deflagrants known, capable of DDT (Deflagration - Detonation Transition) with 123-147% the explosive strength of TNT when detonated at 7300 meters per second (Nitrocellulose (13.35% N) max density 1.2g/cc).
NOTE: It is very important to thoroughly neutralize the nitrocellulose by boiling it in NaHCO3 and in distilled water several times until it tests neutral. It is also recommendable to add 0.5-1% of Urea or diphenylamine in fine powder form to neutralize any remaining nitrogen oxides that could become acidic in moisture and causing accidental ignition of the product.
This product can be stored safely under water or dissolved in acetone (NC Lacquer).
Now I must say the warning. The nitrocellulose produced by this method is EXPLOSIVE and can deflagrate or even detonate violently on shock, friction, or spark when dry. These procedures are not to be attempted, and are outlined here only for informational purposes.

And it's extremely annoying that Powerlabs has been down so much lately, hopefully the domain name ownership problems will be resolved soon.

ice bath schmice bath!
if you want good NC then carry out the nitration for 50 minutes at 40*C.