Fencepost prime - how thick?

[Bobosan]

Wondering what normal thickness on a star might be.

 

Do you roll it on or dust the wet stars?

[Zumber]

depends upon how much your stars hard to ignite. .:-)

 

atleast 1 mm prime would be fine for hard lit star.

 

I will increase the thickness for hard lit stars and decrease the thickness for moderate lit stars.

[jessoman]

I believe it works optimally at 1mm and I wouldn't go over 2mm, including stars which are challenging to ignite. If that amount doesn't work, you may need to alter the heat of the prime.

 

I usually roll it on, its just easier to throw the stars in the roller and spray and sprinkle. But wet is fine too. Its a good prime.

Edited May 17, 2014 by jessoman

[Bobosan]

Thanks guys. I put a layer on some nice round stars by rolling but ended up with rasberries prime. Didn't roll much at all, just enough to coat the star and it burned well after drying. I'm guessing I didn't get the stars wet enough before adding the prime which caused the rasberries. The basic star is Shimizu blue and it rolls great! Nice and round.

[Bobosan]

Update - over the last few days I've been trying to get these blue perc stars to ignite from the star gun. The formula is Shimizu blue #10 (slight variation of #9) from Cannonfuse.com. These stars will not light from the gun with just fencepost prime, pinball prime or with a 2 step prime of BP and the comp. However, if I take some of the previously fencepost primed stars and then go with a BP/comp 66/33 to 33/66 2 step prime bound with NC lacquer (for quickness), they light just fine every time from the gun.

 

Anyone have thoughts on what might be the problem?

[Shadowcat1969]

When you shoot the ones that have only Fencepost on them, do you hear the prime burning off? I would guess that what you are getting is failure of the prime to ignite, even though, from what I've read, Fencepost isn't supposed to need step priming. But when you do move to a step prime it's working, that's why I'm leaning this way.

 

I haven't used Fencepost myself, I was about to because I couldn't get my Shimizu blue stars to light. But then I tried the Spanish Monocapa because of Ned's results and that prime is lighting all my stars, even Perchlorate, quite well by itself. About 1mm of coverage.

[Mumbles]

I am going to assume that these will light and burn on the ground just fine. Fencepost should be more than capable of lighting these stars.

 

One potential issue is that the prime layer is too smooth, and just isn't catching fire easily. The outer coat of BP might be helping this.

 

The other option is that the stars are lighting fine, but then the color layer is blowing out when they fly through the air. Blue stars are notorious for this, and what I would guess is the real issue. Essentially the step prime you're adding to the outside could just giving it more time to slow a bit. In this case a thicker layer of prime in general should do the trick. Fencepost or a layer of fencepost and then BP should work equally well.

[Bobosan]

Mumbles, correct, they do burn well on the ground with the fencepost. I will work some more with the fencepost prime and vary increase the thickness. The first time I rolled the fencepost on I got the rasberries and stopped rolling once the stars were completely dark with prime so may have not been thick enough layer. I did actually see the fencepost burning off as the star left the gun then it went blind.

 

Shadowcat, I checked my chem inventory and I'm lacking the black iron oxide for Monocapa. I want to try that prime also. Have red iron oxide but no black.

Edited May 20, 2014 by Bobosan

[Bobosan]

Three shot test of the Shimizu #10 with Frankenstein prime. Taken this evening. Last gun had two smaller stars, both lit but smaller one dropped out of view of the phone.

 

http://youtu.be/UgxiTwJeEKk

 

 

Edited May 21, 2014 by Bobosan

[FlaMtnBkr]

I think someone reported that the Spanish prime works fine with red iron oxide instead of the black. I couldn't imagine it would make a huge deal to swap them out.

[Bobosan]

I think someone reported that the Spanish prime works fine with red iron oxide instead of the black. I couldn't imagine it would make a huge deal to swap them out.

 

Wondered the same thing. Will research a bit and try a very small batch if there is no major difference or incompatibility.

[Mumbles]

I am 98% confident that red iron oxide will work fine. Remember, these formulas aren't exactly new. In essence it's just a glitter formula with approximately half the nitrate replaced with perc, and half the sulfur replaced with red gum for binding and burning purposes. This is a technique that I've seen from 30 years ago.

[uncrichie]

While on the topic of Fence Post Prime, is there a suggested method for screen mixing and in what order for the chems? Specifically the Silicon and Diatomaceous Earth (DE). DE freaks me out, it feels like crushed coral, can't imagine pushing this through a metal screen? Is this any more/less dangerous than screening BP? Thanks. Kurt

[Bobosan]

I screen all the chems including the silicon through a 40 mesh a few times and then screen DE last. The silicon and DE should pass a 40 mesh easily and probably a 60 mesh also.

[uncrichie]

 

I screen all the chems including the silicon through a 40 mesh a few times and then screen DE last. The silicon and DE should pass a 40 mesh easily and probably a 60 mesh also.

Thanks Bob, Kurt.

[Bobosan]

Monocapa prime made with red iron oxide and applied with NC lacquer works great! Will be rolling some with 75/25 water/alcohol for dextrin test and burn without using NC.