Jump to content


Photo

For how long should my stars dry?


  • Please log in to reply
5 replies to this topic

#1 Pretty green flames

Pretty green flames

    Pyro Forum Regular

  • General Public Members
  • PipPipPip
  • 689 posts

Posted 09 October 2004 - 05:18 AM

I Made some tiger tail (stars) pellets with 10mm diameter.
For how long should i dry them before use.
I used alcohol water mix so i was able to form them.
It's been about 30 hours since i made them.


Thnx
LP

Edited by Pretty green flames, 09 October 2004 - 05:47 AM.


#2 Phoenix

Phoenix

    UKR Forum Ex Regular!

  • General Public Members
  • PipPipPip
  • 544 posts

Posted 09 October 2004 - 08:57 AM

Dry them until they're dry. How long that takes depends on the temperature, humidity and level of air movement.

You can tell if they're dry by weighing them. Obviously, as the solvent evaporates, they will get lighter. Once they stop getting lighter, you know solvent has stopped evaporating, which probably means they're dry. For example, if you started with 100g of dry star comp, and formed it into stars, the mass may change something like this:

Day 1.....120.4g
Day 2.....111.2g
Day 3.....105.7g
Day 4.....101.6g
Day 5.....98.6g
Day 6.....98.2g
Day 7.....98.2g

On the first day, you have the 100g of comp you started with, plus the 20g of solvent you used to form the stars. After a week the mass has stopped decreasing, suggesting that all the solvent has left the composition. They have also reached about the same mass as the dry comp you started with. They may weigh a little less due to some comp being left on your tooling, or a little more due to the addition of cores, if they were rolled (you could weigh these as well, to allow you to be more accurate).

There isn't really any need to weigh them for the first few days, as you know they won't be dry then. What you're interested in is finding out when the mass has stopped changing, and reached it's original level, so I'd just let them dry for a few days, then weigh them, weigh them the next day, and again, and if the mass remains fairly constant I'd presume them dry.

It is worth noting that if the weight were to decrease from the initial 120g, to say, 115g, and then stop, you know that something is wrong, since you only used 100g of comp. This is a sign that the stars are driven in, and the solvent is still there, but not evaporating. However, this is unlikely with 10mm tiger tail stars.

The final, and obvious test for dryness, once their mass has ceased changing, (or, having said that, just after a few days, without bothering to weigh them) is to actually test one. If it performs as it is supposed to, you can seal the rest of the batch up in an airtight container (I like cheap Tupperware boxes). Don't use glass jars for storing mixtures in, if any were to get caught in the thread and ignite while you were screwing the lid on, well you can imagine...

Finally, since it's getting to that time of year where stuff is reluctant to dry outside, I have been looking for a way to build a cheap drying cupboard. What I am using is big, lidded plastic bucket with a jar of anhydrous magnesium sulphate (baked Epsom salts) in the bottom, and a stack of shelves for stars, pasted shells etc above. An old refrigerator would be ideal, since it's airtight, easy to access and already has the shelves in, but I didn?t have one. So far, it's worked well, and it's cheap to construct and run, and very safe, as it will work anywhere.

#3 Pretty green flames

Pretty green flames

    Pyro Forum Regular

  • General Public Members
  • PipPipPip
  • 689 posts

Posted 09 October 2004 - 09:12 AM

Thank you for the explanation Phoenix.

LP

#4 adamw

adamw

    An old Leodensian

  • General Public Members
  • PipPipPipPip
  • 1,297 posts

Posted 09 October 2004 - 04:57 PM

Yes like Phoenix said... until they are dry :)

You can test to see if they are crumbly by squeezing one between your fingers - if it breaks, it is still too wet or you didn't use enough binder (and now you have one star less!)
75 : 15: 10... Enough said!

#5 al69

al69

    Member

  • General Public Members
  • PipPip
  • 26 posts

Posted 19 December 2004 - 05:04 PM

Yes like Phoenix said... until they are dry :)

You can test to see if they are crumbly by squeezing one between your fingers - if it breaks, it is still too wet or you didn't use enough binder (and now you have one star less!)

View Post


Couldn't it be that as you add more dextrin or any other binder and when the star starts to dry the outer layer of dextrin hardens preventing the inner core of the star from drying. So it may look like they are dry from the outside, but inside they are still soft and damp. Surely then it is advisable to use less than 4% dextrin?.
Or am i wrong?. I think that is what used to happen to my stars.
check out my ebay sales
http://search.ebay.c...ssZpyromaster69

#6 adamw

adamw

    An old Leodensian

  • General Public Members
  • PipPipPipPip
  • 1,297 posts

Posted 19 December 2004 - 05:09 PM

It is possible that stars may get 'driven in' - what al69 described. In that case you will not easily be able to tell.

The other way would to be burn a star to test it.. but some 'driven in' stars may burn well, but for a longer time than they are supposed to.
75 : 15: 10... Enough said!




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users