More on Phenolic Resin and cut charcoal stars

[DavidF]

I broke mine up with a hammer and then blade-milled it in short bursts. I screened out the fine stuff and returned the rest to be pulsed again. Ball-milling it didn't work out so well for me. I really can't see how it will work for charcoal stars, based on my limited experiences with it. I'm going to try it anyway, in case it does work well. I plan to coarsely powder mine and then mill it with the comp.

[OldMarine]

Just tried some in my little coffee mill. It broke it down to table salt sized particles that fell through a 20 mesh strainer. Took about 10 minutes to do half a pound. It doesn't take much for a pound of comp so that should last a while.

[NeighborJ]

I've only just begun to experiment with resin but I use a blade mill just as David described but I'm afraid to drive in moisture with the use of alcohol. I'm instead using acetone and mixing it with the resin before adding it to the comp. This ensures it is thoroughly dissolved and moisture free.

Dynomike, I know that wax can be powdered by placing it in the freezer then milling, so maybe you can put your jar in the freezer with the media then mill it again to release the sticky.

Edited October 30, 2016 by NeighborJ

[Seymour]

I've found that milling charcoal cleans the barrel and media very well. If you do "cremora" type powder fireballs this charcoal-resin mix can be used for this (added to your usual fireball powder). Otherwise it is just waste. Crappy rock hard charcoal is excellent, though I know not everyone has charcoal that they are happy literally throw away.

[dynomike1]

I got my mill and media clean. I got all the resin out that i could, then i put a bottle of alcohol in the mill and spun it for about 5min., poured it out then washed with soap and water. Dave i would think after you grind the resin, i wouldn't think there would be any problem milling with charcoal. On most of my colored comps, all i use is a 20 mesh screen. If it will go through, that ought to do it. Thanks neighbor, no way i am going through that again. Looks like i will be spending a long time with my coffee mill tomorrow.

Edited October 30, 2016 by dynomike1

[dagabu]

I am wondering why there is apprehension with using alcohol? I have never seen alcohol drive in moisture and doubt that acetone would create less of a hygroscopic composition since one of the caveats to using any 'quicker drying' solvent is the attraction of water (dew) because of the cooling effect of evaporation.

 

Just dry the alcohol if there are any worries.

 

@Dave, why not make a syrup and use that? You can add more alcohol to make a wetter mix if you need to. The resin will get mixed throughout the comp that way but I agree that it has to fully dissolve in the comp to be fully useful as a binder in high charcoal comps.

[braddsn]

Mike, I have no idea why you are having that problem when milling it. I milled 20 lbs in my blender, then all of it went straight into the ball mill. I had no stickiness at all.. it all ground into powder nice and clean. Absolutely none of it stuck inside my blender, and my mill and media stayed clean too. Maybe I got lucky?? I don't know. Also, I used alcohol with great results, even in 3/4" cut charcoal stars. No driving in.. stars dried through and through very quickly. The charcoal comp called for 6% dex, so I simply omitted the dex and added 6% phenolic. Worked perfectly! Stars are ROCK hard and burn beautifully! For me, this is great because my big charcoal stars do often times get driven in because of the humidity where I live.

[NeighborJ]

IDK, maybe I'm making too big of a deal about the 9% water in isopropyl. If it is not enough water to cause problems then I'll try it. The acetone will cool to below the dew point as air is passed over it but I dry it with a gentle heat in a small tub so air can't get to the stars,once the tub is full of vapor no air gets in. It's almost the same concept as a retort. Quick drying time is of no concern, I am only concerned about moisture and achieving a homogenised mix.

[dagabu]

IDK, maybe I'm making too big of a deal about the 9% water in isopropyl. If it is not enough water to cause problems then I'll try it. The acetone will cool to below the dew point as air is passed over it but I dry it with a gentle heat in a small tub so air can't get to the stars,once the tub is full of vapor no air gets in. It's almost the same concept as a retort. Quick drying time is of no concern, I am only concerned about moisture and achieving a homogenised mix.

 

OH! Gotcha! Im sorry, I use denatured alcohol, not isopropyl. Good point on the 9% water.

[dynomike1]

I just got through pumping 4oz White Strobe W/Phenolic +91% isopropyl. I only have a 12pin star plate.As far as pumping i couldnt really tell much difference in it and Dextrin, except the remence in the bowl was drying a little faster. One thing i did notice is don't try to clean with alcohol, I guess i thought that if it would activate it, it would clean it.( WRONG) I feel confident to roll stares with it after while. Drying time i'll have to wait an see. I don't know why Brad but i caught hell with it. Maybe it was because i didn't grind it first, but what i ground in my coffee grinder didn't want to wipe clean.

Edited October 30, 2016 by dynomike1

[dynomike1]

I checked my stars just now and they appear to be dry, so i lit one and now i have a 1/2" 3sec. white star does phenolic have an effect on Mgal?

FORMULA is

Barium nitrate 51

Sulfer 19

Mgal 18

Potassium nitrate 7

Phenolic or Dextrin 5

Blessers white strobe

[NeighborJ]

I can't really answer your question about the Phenolic and mgal but I do know that the stars likely have the remaining 9% water from the iso driven in. They may seem dry but it is entombed inside the resin and the water will react with the mgal. Today I tried the denatured alcohol as dag suggested and was pleased with its workability but I've not tried any strobes as of yet. They are sensitive to formula adjustments. I'd love to know if anyone else has had any luck with the Phenolic strobe swap out.

[Carbon796]

Phenolic has a higher fuel value than dex, which would probably ruin a strobe type effect.

 

As far as an effect on Mg/Al, it could provide a protective layer. Not that Mg/Al generally needs one.

[dagabu]

Not strobe, sorry.

[dynomike1]

I tried another one just now and got a flitter.

 

All is not lost, now i have another bright white.

Edited October 31, 2016 by dynomike1

[braddsn]

Mike, I have not tried with a strobe star yet. (And now that you have tried, I may stick to dex with strobes.. haha). Phenolic does have a significant fuel value... which is why I still use dex to bind bp, and may still use dex with some charcoal comps. I still have a lot of R&D to do. I did notice on the charcoal stars that I cut, they do seem to burn faster with the phenolic as the binder. I think there are a lot of variables. But, with plain color stars, where the phenolic replaces redgum, the phenolic is fantastic to roll with.

[dynomike1]

I think i will pump some crossettes next with it in them. Next thing is flash going to light them. I know the surface is going to be a lot smoother and i don't see any prime going in that hole.

[Mumbles]

More complex effects like glitters, strobes, perhaps crackle, etc. may require fine tuning or just be incompatible with phenolic resin. They're sensitive enough as it is without adding foreign ingredients.

 

I wouldn't worry about water being driven into the resin. 91% v/v isopropanol is azeotropic alcohol. It evaporates as a constant mixture. Adding solutes can change this of course, but if small amounts of water in stars was an issue for phenolic resin it would never have come into popular use. Water is going to get into your mixtures no matter what you do under conventional means. Even if starting with anhydrous alcohol or acetone, you'll end up with at least a few percent water in there.

 

Keep experimenting, but don't overlook just giving your stars more time to dry. It's as simple as that in a lot of cases. This is not a hobby for the impatient.

[NeighborJ]

Mumbles, I know you are a smart guy and I don't want to disagree with you but I believe your understanding of how an azeotrope behaves at its change of state is incorrect. I've used azeotrope refrigerant on a daily basis and while they create a homogenised blend in a liquid state, they still have disproportionate rates of vaporization. In fact distillation is a very effective means of separation. I am in agreement with you that the water in the iso will have an increased rate of vaporization but not nearly as fast as the isopropyl. I'd be open to info which says otherwise but all my info states that it does not vaporize as you suggest.

[Mumbles]

You're right, I was mistaken. The 91% composition of the vapor is only true at the boiling point. I can't find a good estimate of the vapor composition at room temperature. You can estimate it with Raoult's Law, but this is basically the definition of non-ideal mixing and solutions. If you ignore this very obvious issue, it should have a vapor composition of approximately 95% IPA. Ambient humidity affects this number as well, favoring isopropanol in the vapor. Even with the rather suspect assumption, I suspect this number is probably in the ball park of the correct value.

 

Raoult's law is that the vapor pressure of a solution of two components is equal to the mole fraction multiplied by the vapor pressure of the pure compound. There are corrections for real world interactions, but I don't feel like delving that deep.

[dynomike1]

Brad what do you do with formulas that call for Red gum and Dextrin.

[OldMarine]

Brad what do you do with formulas that call for Red gum and Dextrin.

Replace the red gum 1-1 and the dextrin at only 50%. Dextrin has less fuel value so you can't replace it at an equal ratio.

[Mumbles]

Do you guys happen to know the fuel values for phenolic resin or dextrin? Putting numbers to these things might be useful for making educated comparisons and substitutions. I'll try to look up some stuff when I have some free time if no one has the numbers off hand. There are tables in Shidlovskiy and in Conkling I think. I know it has Iditol in it, which is a phenolic resin itself. Mike Swisher talks about oxygen demand in terms of grams of oxygen required to burn 1g of material, which is basically what I'm trying to ascertain.

[NeighborJ]

A list of common fuels with a BTU content sounds like a wonderful idea, and a list of oxidisers with a useable range of BTUs would be even better. I just had a conversation with a good friend tonight who is a paint chemist. This topic came up and it was in relation to the use of Phenolic resin. He is looking into the possibility of finding a resin and amine which can be mixed and set at room temperature and still retain a fuel value as close as possible to resinox. I can only wish to understand what this entails but I'll be happy to test any results of his research.

[Mumbles]

BTU's are a measure of energy released when something is burned. It's not quite the same as oxygen demand to completely combust a material. One is thermodynamics, one is stoichiometry. Both would be useful however.