Strontium Nitrate (drying)

[Sparx88]

I suppose I should already know this but should strontium nitrate be soft and somewhat packable? Seems it should be a lot dryer feeling. I'm not getting a quality red burn like I hoped, could be it's damp and messing up the ratio/weight of the comps? I spread 5 grams out on a sheet of paper and have it in the food dehydrator at 115 degrees F and will weigh it again after 12 hours or so. Is that an ok way to do it?

[nater]

That should work. Strontium Nitrate is very hydroscopic. I don't use it when the humidity is high. I spread it out on a baking sheet and dry it in an oven at 200 for a couple hours then mill it. Once milled, I store it in a plastic bag with a dessicant all placed in an airtight container.

[Sparx88]

Ok, thank you

[marks265]

Even though strontium nitrate is hydroscopic, I don't worry about trying to dry it prior to using it. I view it as an oxymoron because I'll be wetting the composition to make the star. After the star is made then I begin to worry about the star taking moisture back in.

 

Mark

[nater]

True Mark, I use alcohol to wet and pump red stars rather than water. They never see water, and the phenolic reson makes them moisture resistant so I don't worry about.

[Sparx88]

Having moisture in a chem before weighing would mess up the star comp ratios I would think. I'm not sure yet how much I'm dealing with until I weigh it out after drying. But I'm betting close to 5%.

Edited June 28, 2014 by Sparx88

[marks265]

Having moisture in a chem before weighing would mess up the star comp ratios I would think. I'm not sure yet how much I'm dealing with until I weigh it out after drying. But I'm betting close to 5%.

 

Yes Sparx, that may be a concern. But then maybe the wetting percentage should be less to manipulate the comp with. How about scale error? How much are ya making? Did you try adjusting for the 5 percent in your formula?

 

My point is, and as Nater pointed out, we all make red stars and stars that work using different methods. Further still the extra step of drying the comp as you were asking about is a personal choice. It is not right or wrong as long as you can make a strontium nitrate star light or work as intended. As far as liking the red that you produced it could be other things in the comp that could help or hurt you, which ever formula that is. Or maybe just a bad formula to your liking all together.

Mark

[BurritoBandito]

@Mark265: I won't pick on you too much, but the word is hygroscopic, and that is not an example oxymoron.

@Sparx88: I'd recommend drying your chems and storing them with desiccant as per Naters suggestion. Consistency is important in pyro and what is 5% water this go may be 7% next time. There is just no way to get consistent results, without having an accurate dry weight IMO.

[marks265]

@Mark265: I won't pick on you too much, but the word is hygroscopic, and that is not an example oxymoron

 

When trying to dry it and wet it at the same time I beg to differ

[Sparx88]

I don't mean I'm wanting to dry the chems right before using every single time. I'm talking about drying the chems that are hygroscopic like this before I put them away after receiving them. Most all the stuff I get is already pretty good as far as this goes except the strontium. It's high purity from DuPont, has a good reputation, so I had to ask about the moisture because I really did'nt want to beleive that it's junk. And since I'm new to using it I wanted to be sure I did'nt make any costly mistakes like sending it to the "fountain" creation table.

[schroedinger]

If you dry your nitrate, is also would suggest to dr your solvents.

Depending on which solvent you want to use, the easiest things go use calcium chloride, sodium sulphate, pottasium hydroxid or carbonate.

Where the calcium chloride js normally working for all our ckmmo solvents

[marks265]

Another tid bit is that I had bought a 50 bag of strontium and barium nitrate from Service Chemical. Neither one had a desiccant bag in them.

[Niladmirari]

If you do water or water+alcohol 30%. Stars must be dried at a temperature above 29C (84F). I dry in bright sunlight. This creates the anhydrous (crystallizes) Sr(NO3)2.

If dried at a temperature less than 29C (84F), then a Sr(NO3)2*4H2O, and there will be problems.

[Mumbles]

If anything, you'd be converting the tetrahydrate to the dihydrate around 30C. It doesn't become anhydrous until close to 100C.

[marks265]

All I can figure is that I have De facto monoarid strontimus pellets when I take them out of the dryer. I usually hydrate myself well enough during this process as to not allow the yeast to drop from opening the door too soon.

[Carbon796]

Sparx88, which red formula did you use, what did you wet it with, and how did you prime it ? The Dupont strontium nitrate that I have makes really nice reds. You should check your stars to make sure they are dry. Also, if you used a Kno3 based first prime, you may have some potassium nitrate leaching into the star, which will affect the color.

[Sparx88]

As suspected that 5 grams measured 4.55 after 12 hours of drying. So I dried all of it out and have more accurate dry weight. I was missing a "few" grams of strontium out of a 100 gram batch which is enough to screw with the end result I would think.

 

Sparx88, which red formula did you use, what did you wet it with, and how did you prime it ? The Dupont strontium nitrate that I have makes really nice reds. You should check your stars to make sure they are dry. Also, if you used a Kno3 based first prime, you may have some potassium nitrate leaching into the star, which will affect the color.

 

Ruby Red

 

Strontium nitrate 50
Potassium perchlorate 8
Parlon 18
Magnalium (-325 mesh) 12 (used dark alum)
Charcoal (airfloat) 5
Sulfur 5
Red gum 2 (subbed sulfur)
Dextrin 5

 

Wet with 25/75 alc/water. Pumped 3/8 stars. First primed with 60/40/4, perc/drk alum/dex and then paulownia meal with 10% granulated for rough texture. These are some nice stars, red is a good thing

 

They look great now btw. And taking the advice of drying the stars at a temp above 84 F, using the dehydrator only from now on set at 120 F does the job. I still don't have my new phone or I would post vids. I get a nice purple with this by using 38 strontium, 12 black copper oxide and 12 perc.

Edited June 29, 2014 by Sparx88

[Niladmirari]

If anything, you'd be converting the tetrahydrate to the dihydrate around 30C. It doesn't become anhydrous until close to 100C.

 

Sorry. I have information that crystallizes anhydrous:

http://savepic.org/5761228m.jpg

 

quote: "It is probable that the transition temperature from the tetrahydrate to the anhydrous form is between 30° and 40° C., because at 32° C. both forms have been obtained by crystallisation from solution."

http://strontium.atomistry.com/strontium_nitrate.html

 

So need temperature above (more) 32C (90F).

[Mumbles]

My apologies. I read that incorrectly initially. I thought that said that both the tetrahydrate and dihydrate had been obtained at 32C.

 

It's still unclear to me if drying above 32C will give anhydrous strontium nitrate. Based on the link you provided, and the one below, all it states is that Sr(NO3)2 melts/dissolves in it's own water above 32C. Both links state that you need to heat to 100C to readily remove the water and get the anhydrous product. Maybe the other components of stars will alter the solution/molten Sr(NO3)2 and allow the water to leave more easily.

 

http://books.google.com/books?id=yZ786vEild0C&pg=PA122&lpg=PA122&dq=%22strontium+nitrate%22+hydrate+melting+point&source=bl&ots=WtA59JMw-a&sig=xDbPdOXXcu-3DCEc1oxvNO4KQ04&hl=en&sa=X&ei=b22wU_b4MM-WyASQ4oKwAQ&ved=0CF4Q6AEwCTgK#v=onepage&q=%22strontium%20nitrate%22%20hydrate%20melting%20point&f=false

 

That link may not work perfectly, but the information I wanted to share is on page 220-221.

[Niladmirari]

I mean the selection of the solution. When we cook the composition (red fire) in the water is obtained, strontium nitrate solution (solute) in water. Then dry the stars and strontium nitrate crystallizes. If dry stars below 32C, then formed Sr(NO3)2*4H2O. If dry stars at temperatures above 32C, formed Sr(NO3)2.

 

P.S. Sorry for my english

[psyco_1322]

Last time I dried my strontium nitrate, and weighed it to figure the moisture, it was 18%. That's pretty significant. So you are essentially leaving out 18% of your oxidizer/colorant. Wetting the comp with water has nothing to with the water that you are weighing up as "strontium nitrate".