Binding magnesium stars with red gum and alcohol?

[Potassiumchlorate]

I think this has been up before, but I'd like to hear some opinions on it again. I have difficulties binding with parlon again. It's not that moist here anymore, but the stars will either "swell" or not adhere.

[FREAKYDUTCHMEN]

I guess that should work, but I would prefer to use phenolic resin.

[WSM]

I think this has been up before, but I'd like to hear some opinions on it again. I have difficulties binding with parlon again. It's not that moist here anymore, but the stars will either "swell" or not adhere.

 

I used to roll color changing stars that were parlon formulas. I added about 4% dextrin to the mix and rolled while spraying water. They set up hard and performed well when fully dry. I avoided rolling using flammable solvents for safety AND to keep from seeing a stringy, sticky mess in my star roller. A friend added a little hexane (campstove fuel) to his solvents for parlon stars to help alleviate the "stringy" problem when mixing and cutting them; it worked.

 

WSM

[Potassiumchlorate]

I guess that should work, but I would prefer to use phenolic resin.

 

Hm, I have problems getting the amount of alcohol right with phenolic resin. With red gum it's pretty much like dextrin; you just use alcohol instead.

[Chuleo]

I often roll magnesium stars with red gum and alcohol. It takes a little longer than dextrin based stars with water but it works well. You just have to make sure that your particles aren't too big. (<75um)

[Potassiumchlorate]

Well, I intend to pump them, since I don't have a roller and they are supposed to be big bastards (30mm)

 

The particles are <63µm, so it should be fine then.

Edited November 6, 2012 by Potassiumchlorate

[Potassiumchlorate]

Stil problems. I use 6% Red gum, but it won't adhere

[AirCowPeacock]

Are you disolving the Red Gum in your solvent before adding it to the stars. Huge help! I use 2% Red Gum in acetone to bind everything. 1% works for most compositions.

[Potassiumchlorate]

No, I just spray alcohol on the composition. I have experimented with phenolic resin as a binder and 2% additional phenolic resin in the alcohol, but that doesn't work very well either.

 

It might also be that you guys roll the stars. These big ones I pump.

[dan999ification]

pressing would compact them surely?

 

Dan.

[Potassiumchlorate]

Well, it is a hand pump, not a hydraulic press. I wish I had a hydraulic press, because I really like Mg stars, but they are a pain in the arse to make

[dan999ification]

i would imagine that size would be hard to get good density hand pumping them because of the rubbery parlon springing back, do you use a mallet? maybe worse,

The biggest comets i made were 28mm charcoal based they were fine hand/mallet pumped, im sure that dextrin helped, but no aqueous binders here because of the mg?

I have noticed my parlon/acetone bound stars swell slightly in the first hour of drying, also are cold and soft like fudge, not sticky, maybe the solvent is leaving voids as it evaporates and/or is forcing the star to expand as it breaks through the almost air tight mass in order to evapourate out, even so it should set up fine, mine do.

these are cut and always start square, not a problem for small cut stars but the difference on ( big bastards ) would be clear as you have found.

Anyone else have this problem with parlon stars? Or know why it happens?

 

Dan.

[Potassiumchlorate]

I have pumped 20mm and got them fine. Maybe one should use less solvent for 30mm ones?

[rveline]

Generally, for pumping or pressing stars, the less solvent, the higher the pressure should be. If the comp has both red gum and parlon, you could use a mix of acetone and alcohol, that will keep the stringy parlon problem down, but you still get the binding power from the parlon.

[Seymour]

So long as you keep the alcohol content low. in my experience if you use too much alcohol the binding power of the parlon is reduced for sure.

 

I suggest only about 10% alcohol if you are going to add i to acetone to make parlon binding less stickey.

[pyrojig]

Toluene is claimed to reduce the sticky effects of parlon bound stars, for the purpose of rolling etc. It also is a drying agent as well. May prove to be a good aid with mag stars. One other gem is amyl acetate , it is the primo of primo's , when it comes to a slower dryer, but absolutely water free ( best for mag).

[Potassiumchlorate]

What about ethyl acetate? Awfully expensive in this country (over €100 for 5 liters!) but it is said to work well.

 

I'm not sure if I can get hold of pure toluene. If I can, it will probably also be very expensive.

[AirCowPeacock]

*Whistle* That's hella expensive! Toluene is really easy to get over here. 5 L for a few bucks at the hardware store.

[Potassiumchlorate]

They think it will stop kids from sniffing it. In reality kids get drugs in the school yard or over the internet, of course

[pyrojig]

I think there are other political agendas as well.. sadly it only takes a few idiots to ruin a good thing