parlon bound stars

[MadMat]

Has anyone ever tried using xylene (xylol) instead of acetone as a solvent for parlon bound stars? I was wondering because xylene evaporates much slower than acetone, giving a person more time to form the stars (cutting, pumping ect)

Edited December 20, 2015 by MadMat

[rsambo]

Tom Schroeder has often suggested blending solvents to titrate the rate of evaporation to your required working time and to reduce "driven in" effects. For PVB he has suggested azeotroping with a Toluene / Acetone blend - i'd imagine the same would work for Parlon.

[MadMat]

I was wondering because xylene is listed as a solvent for parlon. The only problems I could possibly foresee is the comp turning into a goey mess or making the "stringyness" problem with cutting stars way worse.

Edited December 20, 2015 by MadMat

[schroedinger]

I would recommend you to not do it. I tried to use washing solvent whixh is aboht 60% Acetone, 20 % Ethyl Acetate, 10 % Xylol. Last ten percent are various contents of these 3. It works good until you come to the point of drying time. The xylene took about 2 months to completly evaporate from my 4 mm strobe stars. Before that they burned bad and refused to strobe.

 

If you got problems with evaporation times, rather think about using it during winter or use ethyl acetate.

[MadMat]

Wow... I have worked with xylene in the past and though it evaporates slower than acetone, it does evaporate rather quickly. Never thought it would take that long to dry in a star. I have worked with ethyl acetate as well and it does evaporate faster than xylene. Plus ethyl acetate smells much nicer

 

Edit: My bad I was thinking of N-butyl acetate..but I still think the odor of ethyl acetate is nicer than xylene.

Edited December 20, 2015 by MadMat

[schroedinger]

Yes ethyl acetate smells not too bad, is much better for the eviroment and isn't listed as hazardous to human health.

[DavidF]

Madmat, I cut parlon-bound stars with acetone all the time. If you are having a problem with them, it is only technique. I use the baggie method as described in the "New to me cut star method" thread in this forum. A good general rule is to use 10% of the comp WEIGHT of acetone, additional. With 20% parlon they cut like a dream. Formulas with only 15% parlon still work well.

 

I personally think the story circulating that anyone needs to extend the wet time or retard the drying time when using acetone is an urban myth. It is actually advantageous to let the stars skin over a bit. I flip my parlon patties like burgers, and cut them in a leisurely fashion. Unless you go out to dinner and a movie after wetting, drying is not an issue. The stringiness is easily dealt with by using a sharp knife with a thin blade, and making sure to cut all the way through, NOT like the people at the sub shops do!

 

I don't mean to sound flip, but lots of us rush to a chemical solution to solve a physical problem. Hope this helps.

[MadMat]

Well I did run into a little problem on time cutting acetone stars. I got sidetracked after rolling out my patty for a couple minutes. The stars formed a "skin" on them and when I cut them they deformed a bit. I didnt get nice neat cubes. That was just one time out of several though. After seeing xylene listed as a solvent for parlon, I just wondered if a little more time would prevent anything like this from happening in the future.

[DavidF]

With the baggie method the acetone can be worked in without evaporating. If you knead a kilo of comp with 100 grams of acetone in a large Ziploc freezer bag the acetone does not evaporate off. Sticking to the bag is minimal, especially with red gum in the formula. Even when the patty sticks to the bag as you peel it back, the loss is nothing to speak of. The surface of the stars and bag are both fuzzy. Good for holding prime. The stars don't have to be perfect cubes. Some deformation, like cutting a loaf of chewing gum, is normal. The more firm the comp is, the better they cut.

When you cut the stars after letting them sit out, sure, the surface has skinned over. And, it will crack as you cut through it. Again, good for holding prime. The cracking of the skin of parlon-bound stars is not the same as the crumbling of dextrin-bound stars. The parlon-bound stars with acetone as the solvent dry to be as hard as rocks, in my experience.

I like parlon-bound cut stars because they are quick and easy to make. I have never had to toss a batch yet. I like EZPZ.

[rsambo]

Dave I completely agree with you on the baggie method; this negates any need to blend solvents. Rolling, again, not an issue. However, I do think that pumping can be an issue - I must admit that in the main i solve this by keeping the comp covered, limiting to a smaller batch size and simply re-adding solvent if it dries. At times there is room for improvement and I have used a toluene blend on small batches of test stars and that does, obviously, increase your working time. The trick is to keep the amount of toluene that you add to a minimum as it's surprising just how little you need.

 

Better still is PVB with either IPA or N-propanol as the binder, in which case there is no stringiness with parlon binding as it's insoluble and the drying time is reasonable with pumping as much of the excess solvent is expelled during pressing. Then again, my current preference is CPVC in place of the parlon and MEK as the solvent which gives the best of all worlds - no stringiness, good drying time and it's so cohesive you can even roll it in your gloved hands without making a mess.

 

Sorry if the last paragraph is off-piste then ignore for the sake of continuity of the thread.

[ExplosiveCoek]

So, regarding evaporation times and binding stars. I did a first time aceton bound cutting trial with acetone bound stars. I used red 1 (with SrCO3 from Spanish PDF). There was no smell left of the acetone, however they were still very crumbly and not hard at all. The center has a different shade of grey than the outside does. Outside looks darker.

Did they attract water somehow, or are they just not dry yet? They were cut three days ago, using 20% acetone as binder. Should be dry by now normally. I didn't check the weight yet, I'll do that next. They just dried in the open (quite humid) air.

Oh, and please don't mind these ugly ass bricks . Apparently too much solvent was used, as they were quite chewing gum like to cut. Next time I'll use less solvent. But these are just meant for cannister filling anyway.

Edited February 10, 2016 by ExplosiveCoek

[burningRNX]

I had such problems when cutting 4% phenol resin and 15% parlon in 1 composition with alc/acetone 50/50 , seems that it doesn't compact well enough, rolling did a lot better,

but its long ago and I don't remember humidity.

[Mumbles]

There is the possibility that your acetone is wet. Water and acetone are miscible. When acetone evaporates, it cools down the stars. It's possible you condensed some water into the stars. Either way I'm not sure what to make of it. Even at 20% water, that's only 4% water overall. That should be able to dry within a few days. Another possibility is that you drove the stars in. Parlon is capable of forming a quite tight seal.

[schroedinger]

I'm not sure about that formula, how high is the parlon content?

 

Also you can easly check whether the stars are dry or not. Put them into a tray and weight the tray. Dry it a couple more days and weight again, if it still loses weight you can be sure they aren't dry.

 

If you really have problems with wet acetone, you can dry it by the use of calcium chloride magnesia sulfate, copper sulfate or pottasium carbonate.

 

Just make sure they are dry and add them to the acetone. Pottasiu carbonate clumps up which is a good sign for left over water. If you use copper sulfate, you need to use the white stuff (made by just heating the blue form, which is the pentahydrate). If water is inside it turns blue again.

[ExplosiveCoek]

Thanks for the advice guys. So it seems again that the moisture content is killing me here. I am getting tired of this issue and ordered a ceramic heater. I'll build a drying box and will see if I can get them hard and crispy.

 

I had the same issue with some whistle mix. Used toluene as solvent for the vaseline, and though it did not smell like toluene, and the weight was the same as the total mass of composition, it probably was still a bit wet. As it had less power than usual, whilst using the same ingredients. Funny how comps mixed with these solvents appear to be dry, but actually aren't.

 

I'll keep you guys posted about the results.

[dynomike1]

I had the same problem with whistle, even using baby oil and acetone seemed like it would take 3 or 4 days to dry.

[ExplosiveCoek]

So just a small update: primed them and placed them in a new drying box. They are rock hard right now. Couple of them were shot out of a stargun with insane speed and everything lit. So next up is testing them in a shell.

 

Furthermore, I put my whistle mix in there too, and got roughly 1% moisture out of the composition. Will check new rockets to see if they're back at the original power now the 1% water/solvent is gone.

 

I'm getting the idea that I should have build this drying chamber way earlier.