Pumping Veline stars

[DaMounty]

I have recently acquired a 1/4" star plate and i'm going to press some veline stars. What I do not know is how much to wet the composition. 10% water or 10% 75/25 water/ipa mix???

 

Thanks

 

DaM

[Mumbles]

What are you planning to use to press the stars? The more pressure you can apply, the less water you need. If you're using a real press, I'd probably start around 8% and work from there. I needed around 10% water with my arbor press for colored composition, and closer to 12% or so for compositions higher in charcoal like streamers and glitters.

 

Straight water or water/alcohol wont change the amount you need by all that much. Make sure to let the composition rest for a bit before pressing to allow water to evenly distribute, and binder to fully activate.

[braddsn]

DaMounty, something to watch out for (don't ask me how I know... lol), be careful of the percentage of alcohol you use in comps containing redgum. I don't go over 15% anymore... because I made a big mess out of a batch of stars once, and it took me forever to figure out what went wrong. The problem was that my alcohol percentage in my water was too high, and was turning the redgum into binder. Just a heads up.

[DaMounty]

Thanks, for the first batch I plan on ramming with a mallet. Currently gathering parts to construct a bottle jack press.

 

DaM

[dynomike1]

Do you have a vise?

[DaMounty]

Yes but not large enough to accommodate the plate.

[Peret]

I don't use any alcohol now in dextrin bound stars. I used to, but it made no difference to the drying time, and it gets messy with red gum.

 

Force your damp compound through a 10 mesh screen before you start pumping. If it's not too wet, it stays as small granules and it's a hell of a lot easier to fill the star plate and shake off the surplus.

[DaMounty]

Hello,

 

How about if I were to cut the veline stars. I have made 100g test batches. Would I aim to wet them in the 20% range?

 

Thanks

 

DaM

[DaMounty]

Hi

 

Another pumping question. I pumped a bunch of C8 stars. My procedure;

 

1) filled the plate with comp tapped to settle filled again, placed press in to compact

2) filled plate again tapped plate to settle filled then pressed. Placed board over plate and hit with dead blow hammer

 

Of course the stars were 1/4" round but in length they were not.

 

Is this normal? or should the stars be 1/4" x 1/4"?

Is it because I did something wring?

 

DaM

[Mumbles]

Were they too long or too short? In general, most shoot for approximately as long as they are wide for stars. Larger stars or comets tend to be a tad longer than they are wide. Charcoal compositions are also more compressible than colored stars. You may find you need to adjust your process some depending on what you're using.

 

Your procedure will depend on what star plate you have, and how deep the female plate is. To fill and press in one shot, you need a female plate about 3.5x as deep as the stars are wide for charcoal stars. That'd be 7/8" in the 1/4" star case. It's closer to 2.75 or 3x for colored stars. With shallower plates, you need to adjust how you granulate the composition, or fill it more than once.

 

For those chinese resin star plates, I had to fill and hand press 3 times before the final pressing/ramming to get stars about the right height for 3/8" stars. I would assume this is a worst case scenario, and would be sufficient or overkill for anything else.

[DaMounty]

The star cavities are 1/2" deep as well as the pins. The spacer is 1/4" on the thin side and as you can see it's 1/2" on the long.

 

My stars are smaller than 1/4" after being pumped. Using the spacer on the thin side. I've been placing the spacer on the pin side when pumping.

 

Am I using the spacer wrong?

 

DaM

[lloyd]

I have no idea what the spacer bar could do for you while pressing. While EJECTING the stars, you want the spacer bars to be on the 'long' dimension upright beneath the cavity plate, so all the stars can be ejected without touching the surface below.

 

As far as your stars ending up too short... well, most cavity plates are from 2.5 to 3 times the height of the star diameter, becaus 2:1 isn't usually enough.

 

With a 'short' plate like that, what you need to do is fill, lightly press to a GAUGED depth (that will change with every comp), fill again, then press for real.

 

In other words, multiple fills with a gentle pressing between to make room for more comp. How deep that first light pressing needs to go will vary by comp, temperature, cycle of the moon, and your mood that day!

 

Lloyd

[Mumbles]

Try a third fill. If you assume the composition compresses 3:1, a back of the envelope calculation says 2 fills will give stars .27" tall. That assumes a full pressure compaction on every fill though, which isn't true with hand pressure. A 3.5:1 ratio should be .24" tall after two, or .31" after three. Accounting for the less than complete intermediate compaction, three fills is probably about right.

 

I wrote a small excel spreadsheet to ball park these for me. Give it a shot if you want.

 

Star plate fill calculator.xlsx

[lloyd]

Mumbles,

That's a great theory, and will work with some comps, but ordinarily it's not great practice. If each increment is fully pressed, the stars usually tend to crack upon drying right at the division line between increments.

 

Of course, he doesn't have this, but the ideal setup is a 3:1 plate depth and an adjustable gauge for inserting the pins to a calibrated depth before filling.

 

On the commercial presses we build, there are both top AND bottom pins each on separate hydraulic cylinders. The bottom ones serve as both the fill gauge and as ejection pins (comets come out the top), and the top pins do the pressing work.

 

Lloyd

[Mumbles]

I probably wasn't as clear as I thought. Just mostly thinking out loud here. I was basically just to ball park the heights, and agree that it wouldn't be the best idea to fully compact the stars between fills for the reason you mentioned. I'm quite honestly not sure how much just hand pressure would compact something, which makes it hard to get a reasonable approximation of height or number of fills. What I meant to describe was something like this:

 

Fill with granulated composition

Lightly compress with hand pressure

Fill remaining space

Lightly compress again

Fill last time (if necessary)

Compact with full force.

 

I thought this was somewhat common practice with thinner star plates among amateurs, but maybe I'm mistaken. The idea being, you are lightly compacting a few times in order to get more composition in before doing the full press. I've never had an issue or hear of issues with stratification of layers while doing this.

 

My thinking was if you know the approximate theoretical height, you could over shoot maybe 20% to correct for the incomplete intermediate compressions, giving you your desired star size. This is why I suggested 3 fills. This is besides it being clear that 2 is giving something too short. If a star would theoretically be .31" tall, perhaps when accounting for the losses from the intermediate pressings, you'll balance out where you want to be. Just thinking out loud really.

[lloyd]

Mumbles,

Your last explanation is exactly right. I must've misunderstood you to mean 'fully compress each increment'.

 

What you say will work fine. Also, understand that a star's _smallest_ dimension primarily determines the burn time. So other than the fact that you couldn't get quite as many in a shell, if they were over-length (even by a lot), it would not change their burn time (by much) from that of 'square' stars.

 

Lloyd

Edited December 15, 2015 by lloyd

[DaMounty]

Ok Here is my first shot using Veline colors.

 

Does anyone have any tips for shooting video on an iphone 5s? First time filming with this phone

 

Film canisterhttps://www.youtube.com/watch?v=7nrJC9eo7Wo

Edited December 20, 2015 by DaMounty