"Bad" sulphur?

[Baldor]

This last weekend I had a lot of troubles. New compositions that didn't work as expected, anaemic BP with a lot of residue... First I though I was doing something wrong, or that the vine charcoal was really bad. Focused on the BP. Finally, I isolated the problem to be the last batch of sulphur I bought. Sublimated sulphur, darker than I'm used to, and gave a green tint to the compositions instead of medium grey.

 

Didn't gave a second thought at first, sulphur is sulphur, what can be wrong with it?

 

After isolating the culprit, I bought dusting sulphur in the drugstore, and all the problems vanished.

 

What can be wrong with this sulphur? The problem is solved, but I'm curious about why this sulphur doesn't work, and not to repeat the mistake. (This last part is easy... Next time I go to the drug store, i will buy all the sulphur they have in the shelves.)

[Aspirina]

Buenos días Baldor.

 

I think sublimated sulfur is better for making black powder, right now I dont know who told me about it... but I know it's more pure, then it's better for black powder. If the vine charcoal is from "Gran Velada" and the kno3 you buy it in "Dalamu" or you are sure that it is a good kno3 maybe the problem is the sulfur but by to poor condition. But what ball-mill you use? How long do you mill it? What balls do you use? How do you granulate the powder? Is there a lot of humidity in the environment? all the factors are important...

My black powder:

KNO3 - Quimics Dalamu (Barcelona)

C (vine) - Gran velada (Zaragoza) / C(poplar) - Homemade

S (micronized) - Quimics Dalmau (Barcelona) -> https://quimicsdalmauonline.com/producto/azufre-flor-agricultura/

6h milling by a 3lb chicago rock tumbler, it works great!

Edited June 14, 2018 by Aspirina

[Baldor]

The problem was generalised in everything that used sulphur, not only BP. First I thought it was the vine charcoal from gran velada, so I tried with some leftover pine known to work. Same with KNO3, form Pirogarage. The problem didn't disappear, so I bought some dusting sulphur at the drugstore and the problem disappeared. First I thought I was doing something wrong, but too many fails in a row didn't sit well.

 

Ball mill is homemade, but is not the problem, worked very well with a 300g load until now. I try to mill BP a minimum of 4h, six if i'm not in a hurry.

 

BTW, I came across some very dry vine this morning, by chance. I should fire the tlud and see what happens.

[Sulphurstan]

Hi baldor.

Good you switched back to the good sulfur. Another (if not the main) problem with sulfur is the acid residues (h2so4, h2so3, so3 etc). With VERY little moisture they can ruin the composition, and this happens mostly after a while (during storage, or when your stars are already in the shell...). My humble experience is I always buy lab grade sulfur and no drugstore sulfur ( in my country drugstore stuff is not that much reliable, maybe in your country that's fine). In Europe a good supplier with good sulfur is pyropowders.

Edited June 15, 2018 by Sulphurstan

[Baldor]

Thanks Sulphurstan. Curious thing, the "bad" sulphur is supposed to be lab grade sublimated. The sulphur that works is from the drugstore. (But labelled as 99.5% pure)

 

I usually buy from pyrogarage (Not this sulphur), and no problems to day. My problem with pyropowders is I can´t find a link to an english version, and I refuse to buy from stores that don't facilitate me the buying process.

[Mumbles]

This is kind of a weird thought, but does the dusting sulfur have clay in it? Stay with me for a minute as this is kind of strange, but I wonder if the sublimated sulfur is TOO good.

 

I've seen vine charcoal mentioned a couple of times as being rather ashy, and not great for BP in the standard 75:15:10 ratio. There is another formula floating around 70:18:12 that I've seen from several european sources. This basically accomodates for the larger amount of ash in the charcoal by increasing the total carbon content and scaling back the oxygen a little bit.

 

I know it's probably total BS, but I was thinking if you had dusting sulfur with clay, if it might be doing something similar.

 

The other thing I'd check would have been to closely examine the milled powder and make sure there aren't hard sulfur granules remaining.

[Baldor]

I doubt the dusting sulphur has clay in it, it says 99.5% pure The problem was the same with vine and pine charcoal, both commercial, and also with W#20 glitter doing nothing but burn slowly. When I said BP was anaemic, I would better said it was dead. I was getting 300g of thrust from rockets that range from 5Kg thrust with "bad" BP to 9Kg with a well milled BP. I made all the combinations possible, since I had some of the old KNO3 and charcoal. Changing charcoal didn't made a difference. Changing KNO3 didn't made a difference. Sulphur made a great difference.

 

Now you mention hard granules... This could be the explanation. I found some very hard granules, I think they were not present in the sulphur before milling, but should examine it. After breaking them, seemed BP, were the same very dark green inside. Could be the cause. Should mill some sulphur alone to see what happens.

 

After the solstice I will make some experiments with the "bad" sulphur, no time to do it now, I have a lot of rockets with their headings to make, bur I'm really curious about what went wrong.

[Arthur]

I have to admit I don't know the answer to the original question, however, the sulphur I used to be familiar with was a creamy yellow with some slightly darker larger particles. Recently the sulphur on the market here is a very uniform very fine powder which is a shade of yellow more like "Saturn Yellow" Hi-Vis fabric.

 

I'm also of the opinion that over the last 10 years sulphur in trade is no longer mined or quarried but a product of refining low sulphur road fuel.

 

Added

As one example;

https://www.albertaoilmagazine.com/2014/04/yellow-mountains-sulphur-oil-sands/

Edited June 17, 2018 by Arthur

[SKC]

Learnt an important lesson.