Silicon based primes

[AdmiralDonSnider]

As far as I remember many APC members prize silicon primes highly for their reliable ignition and straightforward properties. Unfortunately literature seems to become quite sparse when you look for silicon based priming solutions. A formula found in Hardt p.158, that is said to be military in origin is:

 

KNO3 38

Si 38

Meal D 19

Dextrin 5

 

but it contains an excessive (and expensive) amount of silicon.

 

What kind of cheap but still reliable priming solutions exist? Which ones are proved to give good results by APC members? I would like to hear some Si-based light-all solutions...Thank you!

Edited August 22, 2009 by AdmiralDonSnider

[Sambo]

I use greenmix with 10% Si and 5% Al, works every time for me. No problem lighting Veline or high metal content stars. I use it to prime my waterfalls these contain 48% aluminium powder, they light relliably every time.

 

I have found 5% Si and 5% dark Al is actually enough to light most things, although I prefer the reliability of 10%.

[Fred]

95% green mix 5% Si works good.

The Si is from Akzo Nobel (98,6% pure, <100 µm, (exactly 90% < 60 µm, 50% < 40 µm and 10% < 10 µm)).

Edited August 22, 2009 by Fred

[Mumbles]

A lot of people are fans of fence post prime that was developed (I think) by Eugene Yurek. It's pretty self explanatory.

 

KNO3 - 65

C - 15

S - 10

Slilicon - 5

Diatomaceous Earth - 5

 

Mill the BP components. A binder can be added, or it can be applied with gum arabic.

 

Gene recommends a hot charcoal, particularly balsa, for 12 parts of the charcoal, and 3 parts of something slower, like commercial airfloat. Others have proven that any lift quality charcoal will work fine. He also has a theory about the microscopic pores in the DE providing capillary action, sucking in molten silicon dioxide to the surface of the star. It seems a bit far fetched to me, but without definitive proof, I'll remain neutral on the matter. Given this, I imagine any sort of coarse material, or furry material (wood meal) would serve the purpose. Additional silicon can be used to light especially hard to ignite compositions.

 

I've been looking for a "light all" as well. This is about as close as I've seen reported. As you may soon find out, the only light all that really lights all is step priming. I'm resisting going there, but it seems inevitable.

[AdmiralDonSnider]

That´s some useful input. Thanks!

[AdmiralDonSnider]

I´ve got a quick priming question:

 

Friends have recently recommended both Emerald Green and Ruby Red. Will these light reliably using a single coat of Green mix with 5% Silicon added? I try to avoid step priming here...

 

Thanks!

Edited December 21, 2009 by AdmiralDonSnider

[Bonny]

I´ve got a quick priming question:

 

Friends have recently recommended both Emerald Green and Ruby Red. Will these light reliably using a single coat of Green mix with 5% Silicon added? I try to avoid step priming here...

 

Thanks!

 

 

I've never made Emerald Green, but have made 1 version of the Ruby Red (seems to be a few). I used a BP based prime with Si and Al added. I applied the prime in a star roller as a slurry with a final layer of granulated BP to leave a rough, jagged surface.

From what I've read, these stars can sometimes take a while to get going so a thicker prime layer is often used.

[Miech]

I primed both with Bleser AP prime:

 

72 Potassium perchlorate

12 Red Gum

09 Charcoal

04 Dextrin

 

This prime was then primed with some meal dust. For even more heat, substitute 3 parts of the charcoal with german dark or silicon. For general priming of stars I use meal with +10% aluminium and some sawdust in the -40 +120# range.

[TYRONEEZEKIEL]

I also prime both with Bleser AP prime, since in my case, that is a light all.

 

I would say lean toward fence-post prime as I have never heard of a blind star or failed ignition with it. I havent used it before, so Im not sure if it needs step priming.

 

I wonder if an addition of fine Mg in a prime will be sufficient to raise temperatures high enough.

[TheSidewinder]

@Don:

 

If you mean the ones with MgAl in them, my experience with Emerald Green is as follows.

 

All I used was freshly-milled BP, a hot batch with yellow pine charcoal.

 

I cut the stars, poured a few scoops of the mill powder onto the freshly-cut (and still quite damp) pile, then took the drywall blade-tool which I used to cut the stars and just "lifted and turned" the pile until they were well-coated.

 

Put the stars in my dryer for a few days then packed them into my 3" cans.

 

I'm 99% certain they're the ones in my Gallery that I posted. Every one of them lit, as far as I could tell.

 

Ground testing ahead of time was perfect too. Lit one with a kitchen match, just to be sure it would take fire. It did, and surprisingly fast.

 

I used a slightly modified version of the star comp, too. Substituted about 1/4 of the called-for fine (~200 mesh?) MgAl with coarse (~60 mesh?) MgAl. Made a nice sparkly trail on the stars.

[billofca]

Has anyone ever used potassium dichromate (about 5%) added to their charcoal to make a prime? I've never tried it but literature says it makes a good prime.

[dagabu]

Has anyone ever used potassium dichromate

 

If you use it, you need to use it outside, gloves, long sleeves, respirator and goggles. It is a poison, it is carcinogenic and causes immediate dermatitis.

 

I won't use it, period.

 

D

[TheSidewinder]

Potassium Dichromate *IS* a nasty chemical, agreed.

 

In a liquid solution for coating metals, or in a cut/pumped star comp, it's *less* worrisome to me. But it's still something for which I'd do a full "Gear Up".

 

 

 

Interesting, Bill..... I've not heard of it being used as an additive to make a primer, but I'm nowhere near as well-read on the subject as others.

 

I think Dave's right about the precautions. Since it's still dry, and added to a prime mix, airborne contamination would be my biggest worry. If you have a good respirator and proper clothing, you should be fine.

 

I'd do it on a very still day, though, to minimize any such contamination of the workplace where I actually mixed the ingredients.

[Mumbles]

I've used it as an additive in both Veline Super Prime, and Shimzu's #44 (I think) burst. Both worked very well, but I prefer not to use them if I don't have to.

 

The weirdest thing happened. The burst, which was coated on puffed rice cereal, started to mold even with the dichromate in there. I would have thought it would have been like adding paris green to wheat paste, no life possible.

[a_bab]

Mould it's not a form of life. It's proteins/sugars that rearranges itself into green disgusting furry thing

 

I've seen mold on anything, including rat poison. Cr(VI) it's not probably toxic enough. Copper (II) is for sure.

 

 

Now that I've got my silicon, does anyone knows a good simple prime for AP based stars? Something with KP obviously.

[Miech]

I'm too lazy to type it all again .

 

I primed both with Bleser AP prime:

 

72 Potassium perchlorate

12 Red Gum

09 Charcoal

04 Dextrin

 

This prime was then primed with some meal dust. For even more heat, substitute 3 parts of the charcoal with german dark or silicon. For general priming of stars I use meal with +10% aluminium and some sawdust in the -40 +120# range.

[billofca]

I've used it as an additive in both Veline Super Prime, and Shimzu's #44 (I think) burst. Both worked very well, but I prefer not to use them if I don't have to.

 

The weirdest thing happened. The burst, which was coated on puffed rice cereal, started to mold even with the dichromate in there. I would have thought it would have been like adding paris green to wheat paste, no life possible.

 

No doubt about it, potassium dichromate is a nasty chemical. I would hope that any chemical mixing is done outdoors, and with a good respirator.

 

A good preservative for wheat paste is sodium salycitate (used mainly for whistles). I always added about half a cup to a gallon of paste. It turns the paste slightly pink, but it will never spoil or grow mold. You can easily make your own wheat paste by adding flower to cold water and then slowly bringing it to a low boil. Add more flower when it is cooking to thicken the paste to desired consistency. Add water if it gets too thick. Costs nothing to pennies to make. The gluten is brought out in the paste by the cooking, and is the best paste for pasting in shells.

[Mumbles]

I generally make all my paste as needed. I only build for shoots, so my paste only has to stay around for a day or two. It's good to know for the future though if I ever want to make some up ahead of time. I have had good success adding benzoates to stock 4% gum arabic though to prevent souring, odor, molding, and other undesirable reactions.

[cplmac]

I've got a really good Super Prime in the shop, I'll look up the formula and post it when I get a chance. It's a Si prime.