Question about nitrate color stars bound with phenolic

[redbullzuiper]

Hi guys,

 

Ive noticed something wierd last days. I roll all my stars using Phenolic Resin and don't use dextrin anymore, I had no trouble so far.

Until I started making Barium Nitrate green and Strontium Nitrate red stars.

 

This where the formulas I used:

 

Red

50 Strontium nitrate

18 Magnalium (-200 mesh)

16 Parlon

10 Phenolic resin

 

Green

52 Barium nitrate

18 Magnalium (-200 mesh)

16 Parlon

8 Phenolic resin

 

I use Isopropyl Alcohol 99% as the solvent.

 

The difference I noticed directly was that the drying time takes ages somehow. Other star compositions bound with Phenolic are dry within 5 hours and rock hard.

The above formulas were left in a sealed bag (to prevent the strontium and nitrate taking moisture out of the air) to dry. Well, you can't really call it drying as the

alcohol will evaporate.

 

But they didn't get hard and the 4th day I opened the bag again to check them out, they smelled. I have no idea if this is due of the reaction between the nitrates and moisture

neither do I know if the smell was ammonia. I suspected it was, so I burned all the stars at once to prevent any accidents.

 

What I want to know is why this is happening? Has any of you experienced this with nitrate based stars using Phenolic as binder?

 

I find it wierd that the Phenolic somehow didn't make the stars hard, even the prime layer was soft and not rockhard. The prime layer was BP + 5% Si + 5% Phenolic.

Same prime I used on my other stars and they are rock hard without trouble.

 

I personally think it has todo someting with the moisture the nitrates absorb. Unlike Perchlorate or Carbonate based stars, which don't have this issue.

 

This also didn't happen on Kalium Nitrate based star compositions.

[Merlin]

Maybe over 4 days a reaction occurred with the mg/Al and nitrates. Maybe a little boric acid should be incorporated. I'm no expert just speculating. Since you used 99 percent alcohol I wouldn't think a reaction would occur but it would seem at some point. Did you dry in a drying box prior to sealing in a bag? I would have dried,put in a bag and placed ina gamma sealed bucket with a dessicant. Edited September 6, 2018 by Merlin

[redbullzuiper]

Maybe over 4 days a reaction occurred with the mg/Al and nitrates. Maybe a little boric acid should be incorporated. I'm no expert just speculating. Since you used 99 percent alcohol I wouldn't think a reaction would occur but it would seem at some point. Did you dry in a drying box prior to sealing in a bag?

 

Adding boric acid to Magnalium is a bad idea (https://www.amateurpyro.com/forums/topic/12681-is-it-really-necessary-to-coat-magnalium-stars/page-2 or read Prof Shimizu research on Mg/Ai).

 

Putting Phenolic bound stars in a drying box won't help it dry faster neither will the stars become hard. The Phenolic has a very low melting point and when you put Phenolic bound stars in a drying box they are getting very soft. Funny thing is, when phenolic stars are dried, and you put them in a drying box, they get soft again. When you pull them out of the drying box they get rock hard again within 1 hour

 

Thanks for thinking with me Merlin!

[kaotch]

Hey Redbullzuiper,

What about your posting in the Agora that you didn't have time for this hobby?Could you elaborate why you changed your mind!

[redbullzuiper]

Hey Redbullzuiper,

What about your posting in the Agora that you didn't have time for this hobby?Could you elaborate why you changed your mind!

 

Haha, good question. Well, you deserve an awnser and so do the rest of the people who wonder the same.

 

The guy who sold all the stuff and a good friend and girlfriend motivated me to keep on doing it. I was in a sort of crisis, which forced me to focus on other things. Then also suddenly it went bad with my grandmother, where she died later.

So lots of things happend in a short period of time. Things are better now, and this hobby takes away all worries so that I feel calm. I enjoy it and people saw me smiling again when I shot a shell into the air with amazing colors painted the sky

[burningRNX]

redbullzuiper, u said you did them in a bag, how would the solvent escape then?

[Merlin]

dding boric acid to Magnalium is a bad idea (https://www.amateurp...um-stars/page-2 or read Prof Shimizu research on Mg/Ai).

 

Putting Phenolic bound stars in a drying box won't help it dry faster neither will the stars become hard

 

Thanks for your kind reply on boric/ mgal! Ignorance on my part. I am only now making phenolic bound stars. The concern was that heating to phneolics melting point would leave stars soft but drying at ambient temperature would allow the SrNO3 to absorb moisture during drying. Even with 99 % alcohol if the stars are left in a airtight bag the alcohol could not evaporate leaving stars soft. Interesting problem. I may well be missing something since I am new to phenolic binding. Perhaps the answer is that they won't absorb moisture in ambient air. If they do then it would seem that a airflow with a temp well below phenolic melting point in a dehydrater would reduce moisture content of the air while not melting phenolic say a temperature of 105 to 110 F.

[redbullzuiper]

redbullzuiper, u said you did them in a bag, how would the solvent escape then?

 

Haha, another good one. Well, I open the bag few times a day and lay them in the sun for 10 min then put them back in the bag.

[burningRNX]

Maybey not the best stay green option, but you could try some forced heating/ventilation (outside, or strictly controled enviroment,) like were it could burn without no issue, i think a high humidity enviroment could have messed up your drying time

[kingkama]

Why not switch to aceton, so the star will be double bonded, acetone has also a faster evaporation rate, but yes it costs some more.

[Arthur]

Pyro is a hobby that needs time, You need to have enough time available to do the fabrication of the components. You can hurry the drying process but at risk of failure -including spontaneous combustion- increases.

[Merlin]

Do strontium nitrate phenolic stars absorb detrimental moisture during drying at room temperature? If so why not dry at very low temperatures reducing ambient humidity while not softening due to reaching phenolic melting point.

It seems no one knows the procedure for drying these type stsrs

[Mumbles]

Phenolic resin does not waterproof stars or hygroscopic chemicals. It may slow it down somewhat, but it's not a sealant.

 

I don't know if drying them in a bag is the issue, but it sounds incredibly inefficient and probably not very useful.

[redbullzuiper]

Phenolic resin does not waterproof stars or hygroscopic chemicals. It may slow it down somewhat, but it's not a sealant.

 

I don't know if drying them in a bag is the issue, but it sounds incredibly inefficient and probably not very useful.

 

Thanks for the reply mumbles.

 

So how can I dry these types of stars? Putting them outside didn't work for me, although humidity was low. That was the initial idea of putting them in the bag, then everytime I had time I layed the stars in the sun or when it was raining outside, I put them in a room, with room temperature. I put a little ventilator near them, so the air would keep on circulated.

[Mumbles]

Have you tried pre-drying the strontium or barium nitrates? I'm just kind of brainstorming here, but if the salts are wet when they go in, the water might be bleeding out into the alcohol and leaving damp stars or potentially promoting a reaction several days later since the water is trapped by the bag.

[kaotch]

Instead using the highly hygroscopic strontium nitrate replace it by its carbonate. There are many formulae and they produce excellent colours.

[redbullzuiper]

Have you tried pre-drying the strontium or barium nitrates? I'm just kind of brainstorming here, but if the salts are wet when they go in, the water might be bleeding out into the alcohol and leaving damp stars or potentially promoting a reaction several days later since the water is trapped by the bag.

 

No I didn't dry it. Hm, I am going to try that out. I think you are right that this could be the issue. How you dry the strontium? In a drying box?

 

@kaotch

I usualy do, but people suggested to try out the Nitrate in combination with Mg or Mg/Ai as this would produce the brightest and deepest color. Unfortunately I can't test that now :/

 

Any one knows a formula using Strontium and Barium carbonate, which are in brightness and color, equilavent to its nitrate competetors?

Edited September 7, 2018 by redbullzuiper

[burningRNX]

3 things to remeber: ventilation (or more exact passing air over it), low humidity (of that air),and temperature of both air and stars.

That will make them dry.

Do strontium nitrate phenolic stars absorb detrimental moisture during drying at room temperature? If so why not dry at very low temperatures reducing ambient humidity while not softening due to reaching phenolic melting point.
It seems no one knows the procedure for drying these type stsrs

 

 

If temperature is very low, drying takes longer, maybey even longer than what time it takes to absorb the same moisture , I take that as an plausible explanation why hygroscopic stars are difficult to dry at room temp, so I mostly force dry them

 

And yes the will be dry

[Mumbles]

My favorite carbonate stars are Buell Red. You can make a good green by replacing the strontium carbonate 1:1 with barium carbonate.

 

I have a dedicated pyro oven for drying chemicals. I'm not sure what temperature exactly it takes to dry it out. Some people report drying it in a drying box but with zero actual proof they've driven off a considerable amount of moisture.

[OldMarine]

I dry my strontium nitrate in a toaster oven at 250°F for an hour then make my comp, press my stars and dry them in front of a fan if Parlon bound and in the drying box at 175°F if phenolic bound. I toss some dessicant packs in the bucket and call it good.

[rogeryermaw]

 

Then also suddenly it went bad with my grandmother, where she died later.

So lots of things happend in a short period of time. Things are better now, and this hobby takes away all worries so that I feel calm. I enjoy it and people saw me smiling again when I shot a shell into the air with amazing colors painted the sky

through some very difficult times in my own life and during very depressing events, i stepped back from pyrotechnics for a period but came to the same realization. it was such a joy for me! it really helped to clear the cobwebs out of my mind and keep me sane and even a little happy during a time of loss and pain.

 

concerning the drying of your phenolic stars, have you tried adding a percent or two of hexamine? haxamine will catalyze the cross-linking of the phenolic resin and form a very hard polymer. this occurs over a wide temperature range, even to some small extent at room temp over a couple of days. with forced drying around 140 F, they harden up nicely within a few hours. mine always come out crumbly within the first few minute out of the box,but upon cooling, are rock hard.

Edited September 13, 2018 by rogeryermaw

[Sulphurstan]

Regarding drying, what works best for me is putting the wet stars (whatever the solvent) on screens, and force airflow through them at least 3 days 3 nights, 24h a day. ( Longer for charcoal stars) Then, for storage I ALWAYS keep my stars in a bucket, where i put a little box with pierced lid, containing cacl2. I know that this storage is good, coz for water bound stars, the weight decreases little by little everyday for the first 2 weeks, and then stabilize. It's probably a too much procedure, but I don't have to think about slow decomposition etc

 

Another thought: redbull, do you use ethanol, or isopropanol? Here, we cannot get "pure" ethanol, they always add some compounds to make it bitter, and I don't know if these compounds interact with the nitrate and mgal. Isopropanol is more expensive, but "clean"

Edited September 13, 2018 by Sulphurstan

[redbullzuiper]

 

 

concerning the drying of your phenolic stars, have you tried adding a percent or two of hexamine? haxamine will catalyze the cross-linking of the phenolic resin and form a very hard polymer. this occurs over a wide temperature range, even to some small extent at room temp over a couple of days. with forced drying around 140 F, they harden up nicely within a few hours. mine always come out crumbly within the first few minute out of the box,but upon cooling, are rock hard.

 

No, I did not use Hexamine. Ive added yesterday a few percent of hexamine to another comp I was rolling. Just to see what difference it makes, as more people suggested it aswell.

 

 

 

Another thought: redbull, do you use ethanol, or isopropanol? Here, we cannot get "pure" ethanol, they always add some compounds to make it bitter, and I don't know if these compounds interact with the nitrate and mgal. Isopropanol is more expensive, but "clean"

 

I used isopropanol, but currently I use ethylalcohol (the same as ethenol?)

[Sulphurstan]

Hi redbull. I go back o one of the early message from you in this thread.

You write, you don't use dextrin anymore. Is there a reason for that? I have dextrin and phenolic, but preferably use dextrin (easier).

It's just a mater of curiosity for me, if phenolic has advantages that dexrin hasn't ...

Thanks in advance.

[OldMarine]

With phenolic you can have stars dried and primed in just a few hours. I still use dextrin for glitters and charcoal stars since phenolic kills the effect of those types.