Fine Tuning whistle mix

[fiberman]

I got a chance to check the sodium benzoate this afternoon. It did have a slight texture. I will have to wait until the weekend to do any testing.

I will try milling it finer and make another test batch. The Benzoate was advertised as:

“Sodium Benzoate, air milled x fine powder

[NaC7H5O2] -325 mesh, white powder.”

 

I do have a longer spindle and will try that.

I used the ziplock bag method as with the batch that worked previously and also worked with the recent test batch of sodium salicylate. I did not see any white specks but then I wasn’t looking for them. I dried it outside on a sunny afternoon. I will try the ziplock bag in the sun to see if any condensation develops. I hope aging it might also work, (did not do much for me yet).

I guess this batch will end up boosting the breaking charge in shells.

“screened together well” is that done dry? I have been mixing it only when wet and then screening it to break up the clumps just before it is dry. It does dry relatively fast using acetone.

Is there any advantage to going to a different solvent?

Do any of you know of a source that has better perc?

Thanks,

Fiber

[nater]

 

Is there any advantage to going to a different solvent?

 

 

I have noticed harder grains when using lacquer thinner rather than acetone. Whistle made with acetone turns back into powder easier, with lacquer thinner it stores a bit better.

[psyco_1322]

Did you get your benzoate from Skylighter?

 

I prefer to use lacquer thinner too, with Vaseline. I really think Vaseline makes a better consolidating and faster fuel. The smell of lacquer thinner is also more tolerable to me, my noise burns after huffing acetone fumes when I use it. It also seems to dry a tad slower.

 

Whistle is one composition that will benefit from very good, intimate mixing. I usually screen everything but the fuel (saly/benz) at least 4 times through a 60 mesh screen, until it is a homogeneous color. Then carefully, screen the fuel into the oxidizer mix, usually another 3-4 screenings. After that you can dissolve the vaseline into warn lacquer thinner, dump it into the dry whistle, preferably in a ziplock bag, and knead it for a good length of time to get it all well mixed it. Run the wet fuel through a coarse screen, onto a sheet of paper and let dry.

[psyco_1322]

DP Edited February 23, 2013 by psyco_1322

[nater]

SLD tells me that my whistle will never be as fast with mineral oil as it would with vaseline. I tend to mill the perc with the catalyst until it is a uniform color, the screen in the fuel or wet mix it in a baggie.

[fiberman]

I loaded a rocket using the slow whistle and a long spindle intended for BP. It flew well and whistled a little near the end of the burn.

 

I took a small sample (about1/2 gram) of the slow fuel and ground it wet (with water) in a mortar and pestle. When dry it burned MUCH faster. The Sodium benzoate did have some texture and appears to be the main problem.

 

I ball milled some of the Benzoate and made a 100 gram test batch exactly as I did before. I thought it best to change only one thing at a time. It burned fast and whistled reasonably well. The benzoate was a B to get fine enough. It keeps clumping to the sides of the mill and the media.

 

The sodium benzoate came from www.firechemical.com. It was advertised as air milled -325. I plan to contact them regarding it. They may not be aware of the problem.

 

I will try some of the suggestions offered here. Screening it before adding the oil solvent mix and try using lacquer thinner, and Vaseline. Milling the perc and catalyst together sounds interesting also. The perc that I have came from skylighter and is very fine.

 

 

 

Everyone try to keep all your fingers,

Fiber

[psyco_1322]

I understand the want/need to make the fastest whistle possible, but it's not always something that can be easily achieved, or necessary. SLD talks likes it's easy and cheap to just get some drums of high quality Perchlorate. In today's market, it's hard to find that good perc, and when you do, be certain you will be paying the extra price for it. When you can get green drums way cheaper than anything else, sometimes settling for the lower quality is better. Take Dan Thames for example, he bought a life time supply of cheap materials, which are all of the lower quality end, and he has developed his rockets to do work that most people are still dreaming about. It's starting to become evident that slower fuel with longer spindles will out perform the fast fuel with a shorter spindle.

 

Milling the cheap Chinese perc will definitely help up the burn rate a bit, but why bother? I prefer to use the perc straight from the drum, it's already quite fine, and has a very consistent particle size. Milling the stuff will just throw another variable into the situation. We all know mills can tend to grind better or worse depending on the temperature and length of the milling.

 

I have had to mill benzoates before, and it really isn't a fun job. I can tell you that it will work out better if you mill it in considerably cold temperatures. In this case, I will also mill the catalyst into the benz, and sometimes a percent of Cabosil. Whether or not the cabosil makes things better, I don't know for certain, but it does use up this little tub of it I have that really serves no other purpose to me. I also usually mill the benzoate for around 24 hrs, to ensure it has plenty of time to get all milled up. These accounts have been with "chips" of food grade benzoate, a half milled powder might not need all that long.

[nater]

Actually, I don't need the fastest whistle possible. Using a H/U set, slower whistle is a necessity. It just means if I make hybrid fuel my ratio of whistle to BP is different. I was just relaying what I have been taught.

 

The reason I mill the perc with the catalyst isn't so much to mill the perch down, but to get the catalyst evenly dispersed. 10-15 minutes is usually enough. I have not tried to mill benzoates or sodium salicylate. I have heard of many frustrating attempts, so I have just worked with what I have.

[psyco_1322]

Actually, I don't need the fastest whistle possible. Using a H/U set, slower whistle is a necessity. It just means if I make hybrid fuel my ratio of whistle to BP is different. I was just relaying what I have been taught.

 

The reason I mill the perc with the catalyst isn't so much to mill the perch down, but to get the catalyst evenly dispersed. 10-15 minutes is usually enough. I have not tried to mill benzoates or sodium salicylate. I have heard of many frustrating attempts, so I have just worked with what I have.

 

Just to clarify, I wasn't saying there was anything wrong with your information, or your practices. I was trying to point out that, yes, your fuel is usually tailored around your tooling, or if you make your own tooling, the tooling it designed to work best with your fuel. It's easy to tune your fuels if you have a source of consistent materials, and a repeatable method. I am still in preference to faster burning fuels, usually based on salycilate. Even though I have made plenty of benzoate motors, I still have not convinced myself to head down that path to make a better performing rocket. In the long run, I can very well see myself switching over to benzoates (despite the wonderful smell) based on how cheaply you can get the material.

 

Really I don't see that milling the benzoates is as troubling as some people make it out to seem. Yeah you do need to mill it longer than most chems, and yeah it does stick to your media and all over inside your jar, but that's nothing that really causes hassle. It washed away easy with water, and if you dedicate a jar and media, that's even better. If I had an option, I would go with buying a milled product though.

[Mumbles]

I've found that potassium benzoate is easier to mill down than sodium. It seems less sticky. I will typically pre-grind it down to -60 mesh in a coffee grinder or blender. There is a good percentage of dust/flour in there, but that's the smallest screen I had mounted to a frame. For most of what I did with it I just left it as-is. The whistle wasn't great, but it was there. I have milled it before down to a much finer powder. As Psyco said, it works best when it was cool out. I typically shot for an outside temperature in the 60's at most. It still cakes some in the jar, but I didn't have the same problems as I did with sodium.

[nater]

I'll keep that in mind in the future, the K benz I have right now is fine enough already. I like the flame color better than the sodium yellow anyway.

[fiberman]

I milled my Benzoate and screened the items together. I had planned to use lacquer thinner and Vaseline on this batch. The lacquer thinner did not dissolve the Vaseline at a temperature that I was comfortable with so I switched to Coleman fuel. This batch was plenty fast enough for me.

 

I also found that the blender worked much better for me.

 

Thanks again for the help,

Fiber

[psyco_1322]

What exactly were you blendering?

 

Vaseline will dissolve slowly into lacquer thinner, with lots of stirring over some hours. If you put it into a container, and melt the Vaseline, you can pour the lacquer thinner into the melted Vaseline with some stirring, and it will be good to add to the fuel.

[fiberman]

I melted the generic Vaseline and added Klean Strip lacquer thinner. I mixed it for about 20 minutes on a Thermoline magnetic stirrer. I guess I did not allow enough time for it to mix properly. I had everything else ready so I tried the Coleman fuel and it mixed almost immediately. The Coleman fuel costs less and dried reasonably fast on a sunny afternoon (expecting snow this coming weekend). Is there any advantage to using lacquer thinner over Coleman fuel?

Fiber

[psyco_1322]

I've had the Vaseline come back out of solution a little bit if the mix is cools enough. If don't even go as far as putting it on a stirring plate or anything. It's melted with a torch in a beaker, crashed with LT, stirred up really good, taken over to the fuel, added and knead together. Other than a theory of the lacquer thinner maybe causing better integration between particles by capillary action and possibly partially dissolving salycilate and declumping it, not really. It does dry faster, but with slight heat, as you said, most solvents are gone by the end of the day.

 

I personally use lacquer thinner for binding parlon stars. I don't have any need to keep Coleman fuel around really. It's probably about $5 cheaper by the gallon than LT. But then I'm tempted to use it for my next lampare, since it works rather well for them.

[pyrojig]

How well does the thinner compare to the acetone in binding parlon comps? Is it less sticky ? I have wondered if there was ever a way to roll a parlon comp utilizing the parlon as a binder/and fuel. They tend to get stringy with just acetone ( one fellow suggested mixing in a little toluene to stop the strings). As for whistle mineral oil is more expensive, but it bypasses the need to heat and melt stuff. One less step=worth the money.

[psyco_1322]

When cutting with lacquer thinner, you still get some stringy stuff, it might be less, but I'm not sure. It does seem to have a longer working time that acetone, and doesn't burn the nose as bad.

[Mumbles]

Acetone with 10% alcohol added to it is what's recommended in the original literature by Troy Fish to make things less sticky and stringy.

[nater]

As for whistle mineral oil is more expensive, but it bypasses the need to heat and melt stuff. One less step=worth the money.

 

Mineral oil also makes a slower whistle. That could be good or bad depending on your needs.

[pyrojig]

Awesome ! Thanks for the great advise . I remember reading the troy fisher 10% alc. somewhere , but couldnt recall it. Thanks nater, I wasnt aware the mineral oil v.s Vaseline was that drastic in performance .

[fiberman]

I read somewhere that leaving the whistle mix and solvent together for a few hours helped with the burn speed of the mix. I had a test batch started late one afternoon and left it in the Ziploc bag overnight. Once mixed again and dried the next day it seemed to perform better (slightly faster burn and with more whistle) than my previous batches.

 

I have made some observations that all of you were probably already aware of. Sodium benzoate is a pain to grind fine. I dried it in an oven and then tried a blender and ball mill. I just about destroyed a blender trying to get it fine enough to not be able to feel any gritty texture. When I tried ball milling it, it stuck to the sides of the jar within minutes (schedule 40 pvc and pyrocreations tumbler media). I repeatedly scraped it and ran it again. Once when I was scraping it off the side of the sides of the ball mill jar with a Popsicle stick I noticed that some fine particles were reattaching themselves to the just cleaned areas, undoubtedly because of a static charge. I was trying to think of something to eliminate the static charge. I tried milling it in a metal can with no improvement, it stuck anyway.

 

Recently read about Super Whistle mix that has 5% 80 mesh charcoal added. If I added the charcoal while milling the benzoate it might help its gummy nature and the static charge and I might end up with something like a modified super whistle. Added 25 grams (5% of a 500 gram batch) of my pine charcoal to my ball mill and ground it to airfloat consistency. Then I added 115 grams of sodium benzoate and ran it overnight. The next morning the mix was very fine. It looked and felt like well ground meal powder. The trial batch of “Gray Whistle” burned fast and whistled well. It was fasted than my incompletely ground previous batches. My next test will be to see how small an amount of charcoal that I have to add to keep the benzoate free flowing while ball milling.

 

Still my best (and first) batch of whistle was from an ancient container of sodium benzoate that I bought about 1989. The first rocket that I made was a 1 lb and it startled the ___ out of me, and had all the neighborhood dogs barking. Anyone know of a supplier that has truly fine sodium benzoate?

 

Everyone stay safe and keep all your fingers.

Fiber

[dagabu]

Look on Amazon

 

You can look elsewhere as well but look for hammer milled sodium benzoate instead of just plain sodium benzoate. It's going to be more expensive but as you found out, it is a pain to grind!

 

BTW- The reason you are getting faster whistle by leaving the thinner in the bag longer is basic fluid softening. If it works for you, go for it!

 

Dag