From: David Chappell - UK, [EMAIL PROTECTED] Oh dear, I was trying to avoid the anorak chemical stuff but it appears I can't so sorry: Chris Evans said: <<BP contains Potassium Nitrate (75% by weight), an oxidiser which will oxidise (rust) steel in the presence of moisture. Also, one of the products of combustion is Sulphuric acid, a recognised corrosive which will attack steel.>> Yes Potassium Nitrate (KNO3 (all my trailing numbers are subscript :-))is an oxidiser - it is where we get our oxygen for the combustion of BP to take place. There is absolutely NO Sulphuric Acid produced by burning Black Powder. BP is a mixture of one salt (Potassium Nitrate (KNO3) and two elemental solids; Carbon (C), as charcoal and Sulphur (S) in the proportion of KNO3 (75%), Carbon (15%) and Sulphur (10%) For combustion to occur we need fuel (carbon,) oxygen (from the salt) and an ignition source: (remember the fire triangle?) - (The Sulphur acts as a catalyst, and to 'clean up' the process) Chemically, the empirical formula for combustion of Black Powder can be written as follows: Heat> 4KNO4 + 7C + 2S = K2CO3 + K2S2 + 3CO2 + 2N2 If we look at the results we find that our solid, (Black Powder) has produced another solid K2CO3 (Potassium Carbonate) the gases Carbon Dioxide (CO2), Carbon Monoxide (CO) and Nitrogen (N) and another solid, Potassium Sulphide (K2S2) The combustion of BP in an enclosed space (like a gun barrel) produces a volume of gas some 4000 times greater than the volume of the solids used. There is nothing there chemically that CAN produce Sulphuric Acid, or any other acid! What is an 'acid'? - It is a substance which produces the oxonium ion (H30) in water, in other words it releases Hydrogen Ions in water. 'pH' is the measure of a solution's acidity (pH is the reciprocal of the Hydrogen Ion in solution) with 7 being neutral, 1 being the most acidic and 14 being the most alkaline. Try something for yourself, put some BP in a glass of water, shake it up and test it with litmus paper (or Methyl Orange if you can get it) - you will find no reaction! (try the same on some powder fouling if you like - you will get the same result) The main solid produced (Potassium Carbonate) is very similar to Calcium Carbonate (Chalk!) and would in fact react with any acid, which would then be simply neutralised! Calcium Carbonate is hygroscopic, so if left in a gun barrel will attract moisture from the atmosphere and you WILL get rust. Why will you get rust? Well, the iron in the steel barrel is more reactive than the hydrogen in the water and therefore 'robs' the water of its oxygen to form rust (iron oxide) and hydrogen gas. This is the 'normal' process of rusting and it will occur without the presence of fouling if no precautions are taken. All of the products are water soluble, so can be washed out easily. (I still stick to using WD40 until I get home :-) I do hope that this may clear up some misconceptions and even myths about black powder! David. Cybershooters website: http://www.cybershooters.org List admin: [EMAIL PROTECTED] ___________________________________________________________ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics