Shell Pasting Question

[jrin0630]

Ok....I have what may be a dump pasting question. I see all kinds of info that seems to be contradictive. My question centers around "layers" and "wraps". For a 3" paper ball shell, using the 3-strip method, most literature (Pyro Guide for one) suggests 13 "wraps". So first question is, are "wraps" the same as "layers"?? I assume they are. So in using the 3-strip method, each turn around the shell equals 2 "layers", right? And if that is true, how do you get 13 wraps? 6 turns of 3-strip would be 12 wraps/layers. Do you do 1 turn of a single layer to get to 13? Thanks.

[Mumbles]

Given my understanding of the terminology, I would think wraps and layers could be used interchangably. I generally use the term "turn" for times I go around the shell, but specify how many layers deep this corresponds to.

 

I always put an odd layer of total layers on my shells. There are X number of double layers, and a single layer over the top. This is really just to make it look nice and make me feel better about myself. If you are going to do this, get strips that go from pole to pole, and lay them side by side, without ovelapping them much at all at the equator. They're going to inevitably build up at the poles.

 

13 layers seem high. I use 7 of 35# grain long paper tape. I am not going to get into a discussion about it, but 7 to 9 should be sufficient. I put 13 layers on my 5" ball shells for comparison.

[jrin0630]

Given my understanding of the terminology, I would think wraps and layers could be used interchangably. I generally use the term "turn" for times I go around the shell, but specify how many layers deep this corresponds to.

 

I always put an odd layer of total layers on my shells. There are X number of double layers, and a single layer over the top. This is really just to make it look nice and make me feel better about myself. If you are going to do this, get strips that go from pole to pole, and lay them side by side, without ovelapping them much at all at the equator. They're going to inevitably build up at the poles.

 

13 layers seem high. I use 7 of 35# grain long paper tape. I am not going to get into a discussion about it, but 7 to 9 should be sufficient. I put 13 layers on my 5" ball shells for comparison.

 

Thanks. A final single layer was what I was thinking.

[50AE]

Mumbles, 13 layers of #35 seems high for you ? I have to paste a minimum of 16 to have my shell with 2.5mm of clearance between two sides.

[FREAKYDUTCHMEN]

Thats not really important 50AE, you could ad more lift to get a good altitude.

Layers can be decreased simply by adding more booster.

 

13 layers on a 3" shell seems like to much IMO, but if you don't want to add a booster it might be OK. (if you like pasting a lot )

Edited November 25, 2009 by FREAKYDUTCHMEN

[50AE]

Well, I already have the habbit to paste a lot and not to put any boosters. Just straight pulverone.

[JamesH]

I'm having no end of trouble trying get my 2" ball shells to break properly. I'm getting absolutely terrible star ignition. I've tried different burst charges, different number of layers of paper etc.

How many layers of paper does everyone use on their 2" ball shells? Anyone manage to get a good symetrical break from theirs?

Any advice would be very much appreciated

[Gunzway]

I'm having no end of trouble trying get my 2" ball shells to break properly. I'm getting absolutely terrible star ignition. I've tried different burst charges, different number of layers of paper etc.

How many layers of paper does everyone use on their 2" ball shells? Anyone manage to get a good symetrical break from theirs?

Any advice would be very much appreciated

 

Well, the star ignition problem just sounds like inadequate prime. What stars are you using and how are you priming them? I do manage to get pretty symmetrical breaks with my 2" shells despite their size. I normally use BP on grass seed and 1 gram of whistle or flash as a booster. It probably would be better putting 2 - 3 for a harder break, but I'm happy the way it is. In terms of layers, I normally paste a minimum of three which seems to be doing it for me. What burst charges have you tried? Do you have any videos of these shells so we could take a look and maybe see what's happening?

[JamesH]

Thanks for the reply gunzway.

I'm using 1/4" D1 glitter stars primed with BP - surely there shouldn't be an issue with ignition here?!

I have tried H3 4:1 on rice crispies and oat husks with 4 - 6 paste layers. Also tried BP 4:1 on oat husks with 1g 70/30 flash booster pasted with 6 layers. All had very, very poor star ignition. Judging by the sound of the break and the speed and trajectory of the stars that did light, the breaks didn't seem to be overly hard. On the other hand the one with the flash booster made quite a bang and no stars ignited.

Am I over or under pasting my shells?

 

I have another 2" test shell nearly ready to go, this time I used BP 4:1 on grass seed with 0.4g of nitrate flash, pasted with 4 layers of sack grade kraft - the kind used for making potato sacks.

 

I did have several videos of the shells on my old computer, but the hard drive is broken, so I cant retrieve the files. But I have a few photos of the construction and other bits and pieces here -

http://s11.photobucket.com/albums/a152/jamesh22/

 

By the way what kind of flash are you using in your shells and do you have any videos or photos of them?

[Gunzway]

Your shells look great compared to mine, I don't fit nearly as many stars. How's your BP? Is it fairly standard to lift a shell with only 1/10th or does it require more? I personally use KClO4/MgAl flash which has some power behind it.. How tightly do you seal your shells? I seal them so it requires a fair bit of force, pressure and some light taping to seal it completely. Generally when it's very packed and compact it should break harder. Your pasting seems fine, experimenting may be worth it though. But I've pasted some shells many many layers when I was less experienced and never experienced over pasting complications. I paste less and I seem to be having success still so I think you're on the correct amount.

[JamesH]

Thanks for the comment, I wish they looked as good in the sky! My BP is very good, I use 5g of corned bp sieved to the equivalent of 2fg to lift these 2"ers. I pack my shells tightly - no rattles at all.

I really don't know whats wrong, since D1 is really easy to ignite. I also find it difficlut to believe that I am over pasting them, with 6 layers?

What ratio of BP to grass seed do you use and how do you coat them? I use a star roller to coat my burst carrier.

[Gunzway]

Roughly 4:1. Very interesting why you're having problems. So, your stars are supposedly blowing blind?

[JamesH]

Could it be that the shells are under pasted?

I am using vacuformed hemis as described on passfire.com, these have very little strength and rely on the outer paste wraps for confinement. I should think that kraft paper or commercial hemis are a lot stronger. Maybe these vacuformed hemis need more pasting to give the shell the proper strength so that the stars have enough time to ignite before the shell ruptures?

 

What kind of hemispheres do you use?

[Aquarius]

JanmesH: How long do you dry your shells? If my memory serves me right, the vacu-formed hemis tend to soak up moisture a lot more than the pre-made ones. It could be that the water seeps through the vacu-form and into your stars and break. In the worst case, if the outer paper dries fast and locks the moisture inside the shell, it will take ages to dry. One way of preventing this is to give the halves a quick spray of your favourite varnish and keep the moisture out.

[JamesH]

I dry them for about a week in my drying cabinet. I let them dry a bit between pasting layers as well.

I seal the hemis with wet rot wood hardener to prevent the problem of moisture absorption into the shell contents, and to prevent deformation during pasting.

Have you had much success with vacu-formed hemis?

 

I have seen videos of some amazing 2" shells built by another forum member - ThaYankee. The breaks he gets on them are huge and very symmetrical, without looking sparse at all. This is the kind of result I would like to achieve.

[JamesH]

Do the hemispheres provide any degree of confinement? In other words, does it matter if you use strong or weak hemis?

[Gunzway]

Do the hemispheres provide any degree of confinement? In other words, does it matter if you use strong or weak hemis?

 

I would say it does. Having a stronger and thicker hemisphere will inevitably lead to a stronger break than a weaker hemisphere. You just need to paste more with a weaker hemisphere and it'll work out fine.

[scarbelly]

I have one of those BIG ASS rolls of white paper, ya know the ones kids use on easels so they never run out? Well I was wondering if I could use this for pasting. I have no idea of the weight, and I'm sure kraft would be better, but would it work? It's free, and buying rolls of kraft can get expensive.

 

If not, I'll just set up a rig so that I can roll out a "table cloth" every time I go to work.

[Ventsi]

I myself have a "Big ASS" roll of paper from home depot . If I had to guess, I'd say its 70-80lb 4 feet wide. IIRC it was around 7 bucks, kraft ,recycled.

 

I'd say you should do the table cloth idea with the white paper, I do it with my kraft and it makes cleaning[especially when working with Bright Al] a breeze.

[scarbelly]

OK thank you. I guess the table cloth thing will use enough paper that it will still be worth saving the kraft.

[Mumbles]

White paper will be bleached, as are all colored papers. I have heard that this degrades the strength of the paper. It may not be all that strong, but it will make a nice outer wrap on canister shells. I know a few guys who picked up those colored rolls at garage sales and the like, and always have pretty looking shells.

[dagabu]

I myself have a "Big ASS" roll of paper from home depot . If I had to guess, I'd say its 70-80lb 4 feet wide. IIRC it was around 7 bucks, kraft ,recycled.

 

I'd say you should do the table cloth idea with the white paper, I do it with my kraft and it makes cleaning[especially when working with Bright Al] a breeze.

 

Red, green? Underlay paper?

 

D

[Ventsi]

Red, green? Underlay paper?

 

D

 

Its not the red/green stuff its labeled as construction paper, or something of the like. Its just plain brown colored kraft paper. You can find it in the same isle as the masking paper.

[dagabu]

Its not the red/green stuff its labeled as construction paper, or something of the like. Its just plain brown colored kraft paper. You can find it in the same isle as the masking paper.

 

Cool, hell of a price! Guess where I'm going tomorrow?

 

Thanks!

[firetech]

There are a ton of useful things to have, like that stuff. I've been going on a pyro-spending-spree though, I can't stop! I picked up a set of scoops from walmart for $.95 from 1/8tsp to 1tbsp and they are the handing thing to have. I have to say that the most frequently used power tools for me are the miter and my drill press. Then again those are the only tools I have. I'd like a table saw and a lathe. Oh great more money....Dammit