Pumped Stars Composition Compatibility

[gizmothegecko]

Hello everyone. I recently pumped some C6 stars with 10% water and they turned out rock hard, but when I pumped a red star composition ( 51 Strontium Nitrate, 19 Magnalium - 200 mesh, 17 red gum, 17 parlon) with 10% water they crumbled in my hand when dry. Are all compositions not able to be pumped, or do I need to increase the water for some compositions? If not, could someone please point me in the right direction? Any help is appreciated (FYI I'm using a 1/4 by 30 star plate).

Edited January 14 by gizmothegecko

[Carbon796]

Is there a water based binder in the red ? You're not listing one in the formula.

Are you using a press ? If so, 10% would be kinda wet for a color formula.

Edited January 14 by Carbon796

[Zumber]

3 hours ago, gizmothegecko said:

Hello everyone. I recently pumped some C6 stars with 10% water and they turned out rock hard, but when I pumped a red star composition ( 51 Strontium Nitrate, 19 Magnalium - 200 mesh, 17 red gum, 17 parlon) with 10% water they crumbled in my hand when dry. Are all compositions not able to be pumped, or do I need to increase the water for some compositions? If not, could someone please point me in the right direction? Any help is appreciated (FYI I'm using a 1/4 by 30 star plate).

Where is the binder?

If you are using water as a solvent parlon or red gum may not work as a binder ,you have to add dextrin if you are using water to bind stars.

To activate parlon you may use acetone as a binder but it evoporates faster until you finish pressing operation, for red gum to be used as a binder you may need to use alcohol as a solvent. You can use any of one binding system discussed above. Though stars can be pressed without binder at high pressure it's wise to use few percent binder specially for colour stars. 

Also remember Strontium nitrate Red stars are hygroscopic.

Edited January 14 by Zumber

[gizmothegecko]

The formula I mentioned above does not use a binder. I will find a formula that does use dextrin as a binder. Thanks for yalls help.

[Zumber]

Same formula with additional 4 to 5 percent dextrin works well.

[deepakpyro]

What kind of setup you have for pumping the stars?

In my opinion, Red Stars which have red gum as binder is strong and nice results. You can use denatured alcohol to actively the red gum. 

To prevent too much evaporation  keep the star + alcohol mix in a covered box which will reduce the speed to a level. You will have rock solid stars out of it. It will dry in a day or two based on climate. For dextrin pumped stars use about 5 to 7% water based on composition. 

For the above said formula, add 4% of dextrin as binder and start with 5% of water for activating dextrin. Try in small quantities and change the water %

 

[kingkama]

On 1/14/2025 at 2:05 AM, gizmothegecko said:

Hello everyone. I recently pumped some C6 stars with 10% water and they turned out rock hard, but when I pumped a red star composition ( 51 Strontium Nitrate, 19 Magnalium - 200 mesh, 17 red gum, 17 parlon) with 10% water they crumbled in my hand when dry. Are all compositions not able to be pumped, or do I need to increase the water for some compositions? If not, could someone please point me in the right direction? Any help is appreciated (FYI I'm using a 1/4 by 30 star plate).

Ad acetone parlo would act as binder

[SKC]

On 1/14/2025 at 6:35 AM, gizmothegecko said:

Hello everyone. I recently pumped some C6 stars with 10% water and they turned out rock hard, but when I pumped a red star composition ( 51 Strontium Nitrate, 19 Magnalium - 200 mesh, 17 red gum, 17 parlon) with 10% water they crumbled in my hand when dry. Are all compositions not able to be pumped, or do I need to increase the water for some compositions? If not, could someone please point me in the right direction? Any help is appreciated (FYI I'm using a 1/4 by 30 star plate).

Without an additive it is vulnerable to be crumbled. Use small amount of additive as you can, then mix it well. Use less amount of water if you intend to pump. Being a hygroscopic compound, Strontium Nitrate compositions should be added with very small amount of water.

[gizmothegecko]

On 1/14/2025 at 1:30 PM, deepakpyro said:

What kind of setup you have for pumping the stars?

In my opinion, Red Stars which have red gum as binder is strong and nice results. You can use denatured alcohol to actively the red gum. 

To prevent too much evaporation  keep the star + alcohol mix in a covered box which will reduce the speed to a level. You will have rock solid stars out of it. It will dry in a day or two based on climate. For dextrin pumped stars use about 5 to 7% water based on composition. 

For the above said formula, add 4% of dextrin as binder and start with 5% of water for activating dextrin. Try in small quantities and change the water %

 

I'm using a 1/4 inch star plate at 1000 pounds of real force. I tried the formula above (+5 percent dextrin) with 75% water and 25 percent acetone and most of them turned out pretty hard ( but, with enough force I could crumble between my fingers). I used 12 ish % of the solution mentioned. Does that sound about right? About 1/3 of my stars were completely crushable with little to no pressure, but that's because I did not cover the lid so I think the acetone dried up.

Edited January 20 by gizmothegecko

[Mumbles]

Probably a dumb question, but did you let them fully dry? They'll be crumbly until the water has evaporated. Acetone probably isn't doing any binder activation, so it's really just there to cut down surface tension or maybe aid in drying a little faster.

[gizmothegecko]

That's a good point. I let my batches dry for a day and a half and that probably wasn't sufficient. 

[Zumber]

3 hours ago, gizmothegecko said:

That's a good point. I let my batches dry for a day and a half and that probably wasn't sufficient. 

I dry every stars for atleast 3 days in hot weather and 4 to 5 days if weather isn't hot enough. Do remember it reabsorbs moisture even if it is dried out well and you have to store stars in moisture proof bags.

[Arthur]

Every binder has it's own best liquid activator, each binder and activator needs to be compatible with all the chems in each of the star formulae, but a star comp without binder or activator liquid will never harden.