Paper for shell pasting

[AdmiralDonSnider]

I still wonder how thick a kraft paper to buy for round shell pasting. Unglazed virgin kraft is pricey, so I best reflect about my choice before buying. I heard about 40 pound kraft being popular, not sure if this is true. On the other hand my local supply sources what is about a 47 pound (80gsm) only; will this make a difference?

At the same time I´d like to buy a grade I can use for other purposes also, e.g. pasting canisters, rolling cases etc.

 

Concerning round shells, I want to get into it as traditional as possible, focussing at quality at the same time. Many people have proved that paper tapes etc. will not yield inferior results, but forgive me when I focus on traditional pasting with kraft and paste.

 

As far as I know the desired thickness of pasting (amount of layers) is calculated using a formula given by Shimizu; at the same time this formula calls for a known or estimated mean value of tensile strenghts, not for a paper´s gsm or pounds. Do you guys measure these values?

 

What thickness paper (pounds) is a traditional or suggested choice for traditional paper pasting? What about my 80 gsm? Feel free to enlighten me in case I´m taking things too serious ...

[Mumbles]

What sizes of shells are you currently making, or looking to make in the near future? This probably has as much to do with the decision as does anything else.

[ropyro]

I don't do complicated maths on my pasting I just use paper that comes from cement bags, it's a brown, strong paper, wich resists tearing and when soaked in wheat paste is very easily moulded. The cement bags that can be found in my country have 2 or three layers of paper and I usually avoid using the inner layer, wich has cement on it. The outer layer has the brand and other information printed on it and so I pretty much look for the middle layer of these three sheets bags, wich is clean. I normally use 6 layers of paper on 4" shells, wich give a total thickness of about 2 mm; the hemis are also made of the same type of paper, 10 layers/hemi giving around 3mm of wall thickness. Both the hemi's and the finished shells are very strong having a wooden-dowel-like sound when tapped on. The break of these shells is very powerful and symmetrical, using BP on wheat hulls (don't have rice hulls) as burst, with no booster added.

[AdmiralDonSnider]

What sizes of shells are you currently making, or looking to make in the near future? This probably has as much to do with the decision as does anything else.

 

I currently make 3", and 4" in the near future. In the long run I will go up to 6" as well. (note that I refer to round shells)

 

I always thought that you simply add more layers of the same grade paper in larger shells; so in how far does your last statement apply?

Edited November 21, 2009 by AdmiralDonSnider

[FREAKYDUTCHMEN]

Thats right AdmiralDonSnider.

 

Most important thing in my opinion is to use kraft paper for pasting and not cheap ass (many people think it pastes faster) gummed paper tape. Real pasted shells feel, break and look so much better. Especially if the kraft paper is one color. Every commercial paper shell is pasted with normal kraft paper, think about that.

[scarbelly]

Isn't gummed tape more expensive? The reason people use it is mostly because it's faster and easier.

[Mumbles]

Gummed tape is indeed more expensive, and quite a few commercial shells are pasted with gummed tape. Every one made in the US at least, and Chinese factories are getting the machines. I've seen several spanish companies with other taping machines.

 

There was a statistic I heard once that every winner of PGI competitions over 8" was pasted with gummed tape for the last several years. I really hate to say it, but gummed taped shells made on a WASP are indeed superior. The paper layer is more even and identical shells made on a WASP vs. hand pasted, the WASP shell will look better at least 9/10 if not 10/10. If you look at the PGI ball shell competition this year, there were 0 competition wins by hand pasted shells, and out of the top 3 in every category, 10/12 were pasted on a WASP for sure.

 

Anyway, to answer the original question, I would go with a 50ish lb paper. I wouldn't trust canisters that were rolled from 30lb personally. Even twice as many layers just doesn't seem sturdy enough.

[scarbelly]

What about a comparison of hand pasted with gummed tape and hand pasted with kraft and paste?

[AdmiralDonSnider]

These statements remind me of photography, where people often point out the fact that some of the best shots in history were taken with Leica or Hasselblad cameras. That said these brands have gained enourmous reputation. Some people seem to suppose that the shots came out well because the pros had chosen a particular camera, not because of the pros.

 

However, although I consider this discussion very interesting, I´d still be glad to hear what to look for in terms of paper. PGI statistics seem to tell me that gummed tape works well. On the other hand, there are decades of japanese shellmaking telling me that pasted paper should work quite well, too.

 

Edit: seems that I missed Mumbles´ last line. I don´t need the paper for rolling cans, as I already have a roll of #70 for canister cases and other purposes. My concerns refer to round shell pasting solely, where a #70 is suboptimal from what I´ve heard. So how about the #47(80gsm) I suggested?

Edited November 22, 2009 by AdmiralDonSnider

[TheSidewinder]

You're still going to get some opinions, Don.

 

Personally, I use 35# Virgin Kraft to paste all my shells. If I built large shells (=>8") I'd probably paste with 70#.

 

Gummed tape also works very well, from what I hear. And it's faster than paste and paper.

 

I think what's most important is the number of layers and the grain as they're laid down. Whether that's paste-impregnated Kraft, or well-gummed tape, is less important.

[FREAKYDUTCHMEN]

Mumbles, I don't think the PGI represents the whole worlds fireworks industry. If people choose for mechanical pasting it'll be because economical reasons, which is related to time. Putting bigger shells like 8" and bigger on a wasp kind of machine is the easiest way for sure, but for smaller shells and amateurs pasting with paper is easier and faster IMO. I paste my 4" shells in less that 10 minutes. I never read about flash burst charges in 12" shells for example, a lot of flash will reduce the amount of layers very much. This way the pasting also will be less important. I believe it when you say wasp build shells are more often winners, but that won't mean it is because of the wasp. And if it is the wasp it isn't the gummed paper tape, which is a lot weaker than kraftpaper, which means you will need more amount of layers.

I've advised many people to stop pasting with gummed tape and paste with normal kraftpaper and they are convinced. Think about the Japanese shells, those shells are worlds best shells. The Spanish companies pastes their shells with masking tape, most of the time they use plastic shell parts, the pasting is totally not symmetrical, those shells have a bump on the north and south pole, they alomost look like an egg. They break their shells with quite a lot of flashpowder.

 

For amateurs pasting with kraftpaper is the way to go IMO. You just need to know what way is best. Cutting wet sheets with a cutting table goes very well.

Edited November 22, 2009 by FREAKYDUTCHMEN

[firetech]

I have a few questions I've been meaning to ask..

 

Does gummed kraft come in heavier lb? The stuff I use is pretty darn thin (works really well though).

 

How do you all paste your shells (round and can)?

I'm only working with festival ball sizes and below, and my method has worked at those sizes. I'm almost positive that things would change a bit as the size increases though. I wrap my shells top to bottom, rip, and repeat top to bottom so it overlaps the previous wrap just a bit. I do everywhere around the shell as symmetrically as possible until it fits the mortar correctly.

[AdmiralDonSnider]

As my decision which kind of pasting technique to stick to was and is certain, I´d like to focus on the original question if you don´t mind.

 

I´m still unsure if the 80gsm virgin kraft available here is a good investment for this special purpose. Should I look for thinner paper?

 

Other than that, do you usually measure the tensile strenghts of a paper to calculate the optimum amount of layers as Shimizu suggested?

[Mumbles]

I don't bother measuring the tensile strength of my paper. If you are on passfire, kyle showed a rig to test this. I just use his final results as analogous to my own paper. It has served me well in the past. If you're not happy adjust the break or modify the number of layers. It shouldn't take more than a few shells to dial in.

 

I'd say either paper is fine for your purposes. My only concern would be rolling cans from a thin paper of 30-35#. People have done it with 50# for many years, and some actually prefer it when pasting in canister shells. You might want to see if you can get a sample of a paper of this thickness, and try pasting a 3" ball shell. This is going to be the hardest one to do.

 

This website is convenient for converting between units by the way.

http://www.go2paper.com/Tools/measurementConversionTool.asp

[AdmiralDonSnider]

Thanks, Mumbles.

 

Is there a gold standard (lbs, gsm) when pasting round shells with kraft paper? Just wonder what japanese shellmakers and amateurs here use...

 

Edit: Just found the following in Hardt´s Pyrotechnics:

"As a general rule, two or three complete layers of 30- to 40-pound paper will be required for each inch of shell diameter (...) Fewer layers of thicker paper may be used to save time, sometimes with a sacrifice in the regularity of the shell walls." (p.222)

 

Against this background a #40 would be better than my #50, no? Or am I just getting freaky?

Edited November 22, 2009 by AdmiralDonSnider

[Twotails]

Hey, Just for anyone out there, Pyrocreations offers Gummed tape now, and it(IMO is cheap) I use Kraft paper, but am tempted to buy a few rolls (goes from i think 3/4in to 1 1/2 in tape, starting off at like $3 a roll, to i think $7 for the larger stuff) Im not sure the # of paper i use is, got it from walmart, $3 a roll, and seems to work.

[jrin0630]

Hey, Just for anyone out there, Pyrocreations offers Gummed tape now, and it(IMO is cheap) I use Kraft paper, but am tempted to buy a few rolls (goes from i think 3/4in to 1 1/2 in tape, starting off at like $3 a roll, to i think $7 for the larger stuff) Im not sure the # of paper i use is, got it from walmart, $3 a roll, and seems to work.

 

 

I've used the gummed paper tape from both Pyrocreations and Pyro Direct on my 3" ball shells and IMO it works great. I used the standard 3-strip pasting method and it's pretty quick, alot less messy than using wheat paste and works fine.

[TYRONEEZEKIEL]

Forgive me for asking this, but I am curious about using straight masking tape on a shell vs pasted kraft vs gummed tape vs plastic strapping tape with the parallel fibers. I've only used 3 strip gummed tape for the few shells I've done. I am interested, however in the competition on the categories of

Strength

Time to complete

Symmetry

Reliability

Practicality

Cost

Safety?

 

Also, aside from symmetry, what are everyones thoughts on sphere spiking?

[TYRONEEZEKIEL]

Forgive me for asking this, but I am curious about using straight masking tape on a shell vs pasted kraft vs gummed tape vs plastic strapping tape with the parallel fibers. I've only used 3 strip gummed tape for the few shells I've done. I am interested, however in the competition on the categories of

Strength

Time to complete

Symmetry

Reliability

Practicality

Cost

Safety?

 

Also, aside from symmetry, what are everyones thoughts on sphere spiking?

[50AE]

Masking and strapping tapes are:

-very weak

-expensive

-ugly looking

 

Kraft paper is:

-strong

-cheaper

-nice smooth looking pasting.

 

There's no need to try using intraditional stuff in my opinion, I'm sure people have tried already and haven't been satisfied of the result.

[vladou]

I find it's very slow to paste shells with gummed tape (70g) because it require lots of layers. It normaly takes me about 30min to paste a 4" shell. Am I the only one?

 

Freakydutchmen, could you explain us how do you paste your shells with 80g kraft paper?

Edited January 2, 2011 by vladou

[50AE]

20-30 minutes for how much layers? I paste a 4" shells with 10 layers for about 40-50.

[vladou]

8 layers.

[Mumbles]

Gummed tape requires no more layers than traditional paper and paste. I've actually thought one could get away with less layers using the tape as it is grain long, while normal pasting is grain short so that it lays down easier. One must also remember, at least according to Shimizu, that it is more about the paper strength than thickness with regard to pasting. I'm not extremely familiar with the gsm scale, but the chart I am looking at shows that 70 and 80gsm are relatively close, probably to the point I'd consider them almost equivalent for pasting.

[pyrojig]

I had recently made some 3" round shells and used harvest paste. I soaked the 3/4" W strips and broke them in with the paste after they darkened. I was using grocery bags as my source of craft paper. I think they are 70# but being 40%recycled material, I believe that the tensile strength is bad maybe like a 40# virgin craft in comparison. I followed the method that I use normally, and Admiral brought up a pretty good point to me. He said that the "breaking in" reduced the strength even more, because the fibers are being torn.

The breaks where fairly good when put into orbit. So My Q. is: how good is the grocery bag paper for use in pasting shells ,say 3" and 4" ? Shimizu says that it is too heavy of a paper for pasting this size of shell. I guess my overall concern is less pasting being a heavier paper , and bringing the o.d. of the shell up to a shoot-able size ..

 

 

What do you guys do if your shells require a light pasting for a soft break, and the o.d. of the shell is undersized , creating a high need for additional lift powder to get it up to the proper height.? How do you bring these shells up to a conservative Dia. ? Or do you just lift the crap out of them ..... it seems like a waste of good lift.