Liftanddeafen Posted October 28, 2013 Posted October 28, 2013 I've seen this Maltese fireworks video manafacturing where they spike ball shells as apposed to pasting them. Is there advantage to this or is it just a quicker method? Will
Liftanddeafen Posted October 28, 2013 Author Posted October 28, 2013 Lourdes fireworks factory visit- Malta 2013 search on youtube
pyrojig Posted October 29, 2013 Posted October 29, 2013 (edited) I have done this , and it works . But it is more trouble than it is worth . The best application would be for a innerpetal where the builder wants more confinement. This is usually accomplished by good pasting, but not so ,for a inner with many passfire holes punched into it. , I noticed that 3" shells needed more pasting than a 4" . So in the past I had a idea to spike them with twine. They made for a very ugly lemon shaped shell and the burst was not as good as a well pasted shell. The gain would be speed in building , but the breaks will suffer some. Edited October 29, 2013 by pyrojig
LambentPyro Posted October 29, 2013 Posted October 29, 2013 To be honesty it's probably cheaper for them to do it. If you think about it, gummed tape is much more expensive then spiking twine. They have it readily available since that's what they use for their can shells. Why buy different materials if you can apply the concept to both methods of making shells? Since their very skilled already, probably not difficult for them to do it. Don't know about anyone whose tried it, but I'm not sure how difficult it would be to do. Try it and post the results, OP?
Liftanddeafen Posted October 29, 2013 Author Posted October 29, 2013 Yes I am interested in trying it but it seems like it's only real application would be for an inner petal so when the hemispheres have several holes in it the string doesn't stop the flame propagation.
nater Posted October 29, 2013 Posted October 29, 2013 Plain paper and paste is cheaper than twine. Using gummed tape on shells is a recent practice. There must be another reason they spike ball shells.
Shadowcat1969 Posted October 29, 2013 Posted October 29, 2013 In the video (it is actually video 2 of the 3 in the series) they are using free paper harvested from animal feed bags (they show those and mention that they get them free from local farmers) and paste. They are also using disks of paper, rather than strips, to paste the shells in, two disks per layer on a shell. I don't know if this pasting method may have something to do with the spiking. They didn't discuss the spiking but it is plain to see it under the pasting layers.
Arthur Posted October 29, 2013 Posted October 29, 2013 Beware the string size. My limited experience of string bound material is that it takes more space than paper pasteding.. Your shell may not fit your intended mortar.
Shadowcat1969 Posted October 29, 2013 Posted October 29, 2013 Actually Arthur, upon reflection I think you may have hit the nail on the head. Using the spiking increased the diameter of their shells without having to apply an additional 12 or 15 layers of paper. It may be a time or labor saving device on their part.
chemtech89 Posted October 30, 2013 Posted October 30, 2013 (edited) Good call shadowcat that may verywell be the reason. Not to disagree but to add; when skimming through the video I was given the impression they make their own hemies. If so they would just make them larger to fit the bore. It must at least be a combination of the two because twine will/ must increase the diameter of the shell in addition to increasing strength. As noted before it does not at all seem to decrease cost. With that in mind I agree with shadowcat, labor/ time saving. Strength and size at the same time. Edited October 30, 2013 by chemtech89
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