A little help with prime comps please?

[jwitt]

Briefly- I'm back from 9 days in the woods- mud, rain, snow, and soaked canvas tents to pack up when we left! Oh the joy! I lost 5 pounds of blubber and had a lot of "fun."

 

Now it's back to the pyro project I've been talking about in the newbie section and my blog. Already having a nice bucket of KClO4, I grabbed most of the chemicals I need for a couple Veline stars to add a little variety to my shells' mainstay- charcoals.

 

I did this before I realized how nasty Potassium Dichromate is. I really looked forward to using the Veline "super prime" because of the geeky love of neat chemical reactions.

 

I could work with it, if I'm very careful- I'm thinking tyvek suit in addition to other PPG (personal protective gear) in addition to separating the prime making and star priming processes from all other work, and doing the priming at the end of a work day so everything can be thoroughly cleaned after it's done.

 

For all that trouble and potential health risk, it still sounds like the easiest way to go.

 

But I have read up on Fence Post Prime:

 

Source: Eugene Yurek

 

Potassium Nitrate 65

Charcoal Airfloat 12

Sulfur 10

Diatomaceous Earth 5

Silicon, 325 mesh 5

Charcoal, spruce, ball milled 3

 

Maybe a step prime- fencepost on the veline stars and BP atop that?

 

 

Another thing I'm not up to speed on is the solvent for each of these primes. I'm planning on priming these stars after drying, and I assume I'll use a slurry...but my ignorance is showing here. Acetone ought to do the trick? NC lacquer? Argh!!!

 

Thanks for all the patience and help so far! I'm almost out of the research phase and into little test batches! (I can see it now, I'll be back in a few weeks..."waaah my stars don't work")

[dagabu]

From Gene,

 

"As far as binder, I mix it without one and spray 4% gum arabic. Others have added dextrin or have even put it down with some NC lacquer and all have gotten good results. Basically stick it to your stars with anything you want so long as what you're using burns (hehe). "

 

D

 

 

[jwitt]

Argh! Now I remember - I read that very quote somewhere not long ago!

 

Into the pyro notebook (the only micro$oft program I will ever promote is OneNote...flippin' awesome, it is)

[FREAKYDUTCHMEN]

Don't use more than 3 - 3,5% dextrin in your prime.

[Bonny]

You could also use this "Veline Style" prime by Pax

 

Potassium Perchlorate 62

Charcoal Airfloat 22

Magnalium, granular, -200 mesh 7

Dextrin 4

Aluminum, flake, dark, American dark. -325 mesh 3

Copper(II) Oxide, black 2

A few % of woodmeal or fine sawdust helps too- makes the stars fuzzy

 

Apply with water and maybe up to 25% alcohol

 

Give the stars a final coating of meal powder.

 

This is what I use on Veline stars and it works well for me.

[jwitt]

Allright, now I've got some options, and I can avoid dichromate.

 

Cost of prime materials isn't going to be a huge factor this time around, since the majority of my stars are going to be charcoal...color stuff for a little "spice" here and there as pistils, and a couple shells using all color stars.

 

FYI I'm doing blue and red Veline, and since I have some Strontium Nitrate, I might as well make some of those as well...soon, so I can get 'em mostly dry and then toss in a desiccant chamber to try to pull the water out of the hygroscopic nitrate.

[Mumbles]

I'm curious why you're recommending not adding more than 3-3.5% dextrin to the prime Freakydutchman.

[FREAKYDUTCHMEN]

because I'm told hehe.

 

Dextrin doesn't do anything for a better ignition. The prime burns better, faster and hotter with less dextrin.

3% is enough to hold that final layer. There are even some glitter mixes that only require 3,5% dextrin, I mean the whole star. The more contents that doesn't bind well, like charcoal, the more binder you'll need (shimizus willow for example).

Also, wet the star (surface) well so the prime and star composition mix up a bit and the final layer also glues better on the star.

[Bonny]

because I'm told hehe.

 

Dextrin doesn't do anything for a better ignition. The prime burns better, faster and hotter with less dextrin.

 

 

It may burn hotter, but you don't want the prime to burn off too fast, which is why many primes are screened only rather than milled, resulting in a slower more slaggy burn.

[FREAKYDUTCHMEN]

Primes need hot mealpowder (and additives can be screened in).

 

And by the way, like I said, make the star wet enough so the prime and star composition mixes up a little bit. So you don't need slag, the prime ignites the starcomposition in one time. Slaggy primes makes stars that don't ignite all the same time.

Edited March 25, 2010 by FREAKYDUTCHMEN

[explomaan]

That sounds logical to me. I have rolled some Shimizu organic violet stars colour changing to orange and I'm not sure how tho prime these. Because of the coulour change, the stars have to ignite on the whole surface so the final layer should be a pure black powder layer. But is there need for a hotter prime underneath it like blesser or black powder with some metal?

 

Shimizu organic violet:

Potassium perchlorate 61.3

Red gum 9.1

Basic copper carbonate 5

Strontium carbonate 7.4

Parlon 12.4

Dextrin 4.8

[Miech]

For a neat effect I would use a changing relay. When using a changing relay, you usually need to prime the star under that layer, because most relays don't burn very hot. When not using relays, a prime between the two colors usually isn't needed for proper ignition, given that you rolled your stars decently round.

[FREAKYDUTCHMEN]

I've had good results with only changing relay and not another prime. The cores were beachle purple. For shells smaller than 8" I would not recommend to use a changing relay. In most situations collor to collor don't need prime between them.

[jwitt]

I've settled on a fencepost prime. I thought Si powder would be difficult to get and expensive, but in my (almost) final chemical order, an $8 pound of Si powder is on its way!

 

When I saw the 3% Dextrin comment, I thought "yeah, that makes sense, don't want to retard the burn" but after more reading and considering the comments here, I understand why you would not want an extremely fast-burning prime layer.

 

A few days ago, priming was something I was not looking forward to- a means to an end. After research (and everyone's comments) I am intrigued by the process. Alchemy! Plenty of options- from prime composition, to method of priming stars, to solvents. More fun than I thought it would be.

 

By the way, I'm not rolling stars this year, but nonetheless, rolled star info doesn't go to waste for me, since all these things are related in some way.

[dagabu]

There are so many great cut stars that rolling can wait quite a while. I like to roll stars when I need some help in the patience department, one cannot hurry rolling stars.

 

D

[Bonny]

That sounds logical to me. I have rolled some Shimizu organic violet stars colour changing to orange and I'm not sure how tho prime these. Because of the coulour change, the stars have to ignite on the whole surface so the final layer should be a pure black powder layer. But is there need for a hotter prime underneath it like blesser or black powder with some metal?

 

 

 

I've had good results with only changing relay and not another prime. The cores were beachle purple. For shells smaller than 8" I would not recommend to use a changing relay. In most situations collor to collor don't need prime between them.

 

I agree with FREAKYDUTCHMEN and think unless your orange is a Mg orange or something very hard to light no intermediate prime will be needed. Keep the size of the stars (orange layer and final size) nice and consistant, with a good outer prime to get them going evenly.

 

Plenty of options- from prime composition, to method of priming stars, to solvents. More fun than I thought it would be.

 

You'll probably find as many primes and methods as people making stars and shells. A lot of similarities, but each has their own way.

[dagabu]

I do an outer coat of meal no matter what the star is, NC will seal chlorate stars (I do not recommend this) and fencepost prime is the ticket to any really hard to light stars.

 

D

[jwitt]

Yeah, most of my stuff- Granite, D1 Glitter, TT/Chrys/what-have-you...these will get a hit of "Meal" which I imagine will be my leftovers from screening out my lift powder.

 

Cut star priming ought to be fairly simple- dust the pancake like in bread making.

 

My pumped color stars (Veline blue and red) are gonna get fencepost. I foresee lots of small-batch star pumping sessions on weekdays for D1 and Veline. I guess I'll prime the pumped D1 with a painted-on slurry and a dip in Meal.

 

Looking forward to rolling some "charcoal to color" type stars in the future...maybe for 2011.

 

(Only days away from beginning, now that the chem & star pump orders are placed...and I can start crushing up alder for my soon-to-be-purchased yellow-painted $175 mill)

[Bonny]

Cut star priming ought to be fairly simple- dust the pancake like in bread making.

I guess I'll prime the pumped D1 with a painted-on slurry and a dip in Meal.

 

For the cut stars it still depends on the comp, some comps will need something hotter than meal to get started.

IIRC D1 lights quite easily, I don't think I used to even prime mine and they worked just fine, but it's still better to give them a meal prime to be sure.

[explomaan]

Thanks for the helping!

I already added a small layer of changing relay before I asked about it so next time I will leave it out. From the core to the outside the stars contain:

 

-core: Coriander seed (not on the pictures)

-Perigrin organic orange

-Changing Relay #2

-Shimizu organic violet

-blesser prime

-meal

 

Orange organic Perigrin:

Potassium perchlorate 68

Red gum 12

Calcium carbonate 11

Charcoal 2

PVV 2

Dextrin 5

 

Changing Relay #2

Source: Shimizu[1], page 187

Comments: This type of composition is put between two color layers in a star to create the illusion that all the stars change their color clearly and simultaneously in spite of slight deviations in manufacture.

Preparation:

Potassium perchlorate.............................81

Red gum...........................................13

Soluble glutinous rice starch.....................6

 

Prime (bleser)

KClO4.............75

Red gum...........12

Charcoal..........9

Dextrine............4

 

 

 

The layers are small but I hope not to small

[FREAKYDUTCHMEN]

How thick is that changing relay layer?

The BP prime is too thin IMO.

[Ventsi]

Let us[me] know how that orange works out, I'd be interested in a video.

[explomaan]

Oke, I made a 4 inch shell made of the stars shown before. It was a 4 inch shell (my first 4 inch fired) and I'm pretty happy with the result.

 

 

Of course there are some thing that need to be ajusted. Because the meal prime was not that thick, did I break the shell a bit soft. The shell clearly should go higher. The stars changed not at the same time because a lack of star sorting devices (I only have 6, 8 and 10 mm untill now).

[Ventsi]

You seem to be doing the same thing I do. Using longer burning stars and a stronger break to get a HUGE burst for the shell size though it seems you went a bit too far. Still an excellent shell, and I loved the rising tail on it.

[jwitt]

Got my "almost final for 2010" chem order including some Si powder yesterday.

 

Anyway, I'll be burning fence posts in rainstorms presently.

 

Couldn't resist monkeying around with my expensive MgAl powder, so I made a little batch of "flare powder" with some perchlorate and burned it in a tube. Mmm bright light!