Lil_Guppy

Going through some of my odds-n-ends boxes, I found a batch of 5mm bottle rocket tubes which had had the clay endplug rammed in (but no propellant/header/etc), and I thought I might as well complete and use them so they are not taking up space (that's my excuse anyway ). I noticed, however, that the endplugs were quite easy to push out, as if either the tube had expanded slightly (unlikely), or the bentonite had shrunk slightly over the months of storage. I've never had this problem before, as everything I have made has been used within the week. However, it is a problem I would like to fix in case I decide I want to make a large batch of rocket motors one weekend, for storage and use over the months.

The bentonite 'clay' I am using is from a local ceramics supplier which lists it as Bentonite with the following description:

--
BENTONITE
Used in glazes as a suspending agent.

Al2O34SiO22H2O.

An extremely plastic colloidal volcanic clay that is invaluable as an additive to bodies to increase plasticity (up to 5%) and to glazes as a suspending agent(up to 3%),but it must be added to the dry ingredients.It has a high shrinkage rate at stoneware temperatures.
--

The reason I cut-n-pasted that was in case there are varaitions of bentonite which would have a different description/use.

Anyway, back to the issue at hand. I have read that treating bentonite with wax dissolved in a solvent (such as the tea-light candle wax and petroleum spirit described on Alan's site) reduces crumbling and sticking of the resulting plug after ramming. Could this also provide a "waterproofing" characteristic to the bentonite to help prevent/retard the plug absorbing moisture and causing it to shrink?

If anyone else has any other suggestions, that would be great.

Cheers,
G

Just wondering if anyone happens to have a copy of John Donner's "A Professional's Guide to Pyrotechnics". I recently bought a copy from an online place, and it turned out to be a rather dodgy photocopy job (not happy! ). Most of it is readable enough for me, but there is one picture that is simply not readable at all. I was thinking about re-typing the book so I can at least try and reprint it (I know it's not the original, but its better than throwing it out and wasting my money ), but I would like to have a better (i.e. legible) version of the picture. The picture is on page 52, and is a diagram of T.G. Hitt's Flashcracka. So if someone has the book, and doesn't mind scanning it, it would be much appreciated.

One of my fathers friends, who is a collector, found a small tin one day. He opened it up and found it contained small packets, each of which contained what looks like a match, and and unknown item. I took some pictures (which are below) in the hopes that someone can help identify the item. The items are old(ish), with a date estimated around the 1960's (estimated from the plastic packages, and the sealing method). Here are the pictures:









The tube like thing poking out from each end of the mystery object looks like copper, and it is hollow, but blocked with something near the halfway mark.

It would be greatly appreciated if anyone has any idea what these might be, or where an answer could be found.

I currently have a virtually unlimited supply 2inch ID cardboard tubes which are thick enough for mortar use, and so I was thinking about constructing my first shells to fit these tubes. While I understand that it will be hard for me to get a symetrical break from these shells, and they may also be harder (more fiddly) to make given their small size, I prefer to start out small and work my way up. This way I can get the basics down pat, and also save on chemicals (I'm a cheap so-and-so I know). I have done a reasonable bit of reading with regards to canister shell construction, and their lift charge requirements but none of the sources covered shells of this size. I was wondering what diameter the shells should be. While I realise that generally one would use a case former that is ?inch smaller than the mortar tube to allow for pasting, spiking and wrapping, my question is does this rule apply to small shells, or are the shell/former diameters different to this rule.

Any other advice on small canister shell construction would also be greatly appreciated.

Thanks