Loading HTMD when wet?

[HVD]

I was was wondering when making blastig caps you have to load and press the primary when it's wet, yes? So in my particular case (if i were ever to make a blasting cap:-) I would be using HTMD: should I use water or alchohol to moisten it? And if it's alchohol what type?

Cheers
HVD

[CyclonitePyro]

Hey, you wouldn't be loading your HMTD into a metal cap would you?!
You could if you varnished or coated the inside of it.
Also, make sure whatever kind of alcohol you use, that the HMTD is not soluble in it, or else when the solvent evaporates, large crystals of the explosive will form and be more sensitive.
I forget what HMTD is soluble in, so maybe you could use some oil and leave the oil in it, it might boost the VoD.

[DBSP]

I've loaded HMTD in metal caps without coating the inside, but these caps have been used within an hour so I don't think any HMTD should have reacted with the metal in such a short time. I find HMTD easier to press and obtain good densitys. The crystals seem to cling together better than AP that don't like getting intimately with each other.

[Yi]

I use aluminium tube for my dets. Surely, HMTD won't react with Al2O3?

Also I doubt it would be a good idea to add oil to a primary. Just use it dry, or if you press it with something it should be done with a solvent that will be allowed to evaporate before use.

[kingspaz]

i agree, oil is a bad idea. all you will be left with is an incendary device (look in the plasticising HMTD topic).
yi, the HMTD will not react with the Al2O3 (layer over the Al) but its only a thin layer and will react with the metal underneath. i'm sure someone posted pictures of a 2month old Al HMTD cap.
not sure how much risk it actually is but i'm sure its better to be safe than limbless.

[Anthony]

When using Al tube (annodised) for peroxide caps, I press a clay plug into the end and then stand it on the hot plate. I then drop little bits of wax into it until it is full of liquid wax. Then I pick it up with pliers and flick all the wax out, this leaves a layer of solid wax coating all the surfaces inside the cap - just in case.

[Zambosan]

Don't peroxides react with metals?

<small>[ July 18, 2002, 01:40 AM: Message edited by: Zambosan ]</small>

[Pu239 Stuchtiger]

Copper catalyzes the decomposition of peroxides.

[mark]

Use vinyl tubing guys. Its water proof, nothing reacts with it, and their is no troublesome shrapnel.

[Zambosan]

I thought so... lots of available oxygen.

<small>[ July 18, 2002, 01:40 AM: Message edited by: Zambosan ]</small>

[Anthony]

The trouble you can have with plastic tubing is that it bends under the pressure of pressing the cap. The finished cap can also flex, potentially grinding the contents together...

HMTD reacts with no end of metals.

[Pu239 Stuchtiger]

Try this...
Take your vinyl tubing, and seal one end. Now take a metal tube that has a slightly larger diameter than the vinyl tube. Seal one end of the metal tube. Now fill up the metal tube with a two part epoxy (a kind that can harden without air). Quickly insert the vinyl tube fully into the metal tube, and wipe off any displayed epoxy. Let the epoxy harden. After it has hardened, you have a tube with all of the positive aspects of a vinyl tube and a metal tube, but none of the negative aspects.

[ALENGOSVIG1]

But there will be a gap between the actual explosive in the cap and the explosive you are trying to set off with the cap becuase of the thick walls of the tube. Therefore more explosive would be needed to set it off. I just coat the inside of my tubes with wax.

[nobody]

Hello,
I use this little test-tubes for building caps. The glass will be pulverized while the detonation, they are cheap and easy to load. Of course they have to be handeled carefully, but I think all caps are sensitive.

[10fingers]

The vinyl tube has possibilities as long as it's fairly rigid. I usually use brass or aluminum 1/4 I.D tubing. It's fairly simple to coat the inside with varnish or wax. Varnish is slightly better because it won't scrape off as easily during pressing as wax.
Another possibility is to use a common drinking straw and slide it into a piece of 1/4 metal tubing.

[MightyQuinn®]

Somewhat off topic, but my mind and fingers lead me in the direction the thread has meandered.

After reading this thread it struck me; I have the PERFECT tubing for making caps.....

I have obtained some of the tubing used in fast food restaurants to ferry drinks to every corner of the cholesterol factories. If you have seen it, you know what I mean. Its a semi-flexible hose with fibers in a mesh pattern between two layers of fairly stiff, translucent plastic. When you cut it in pieces of about 3" they take a good bit of force to bend (preventing the possible friction event) and are tough as nails.

I sealed the end with a hot glue plug and can fit almost 3g of lightly (read: F*CKING carefully) tamped AP in along with a fuse/ignitor.

I am still running tests with AP and the tip of the hot glue gun before I attempt to seal the deal with it. So far, it seems that even at high heat for several hours I cannot get AP to do squat with even the metal part of the iron. I even sprinkled some AP on the glue residue on the heating tip and let it sit for a long...well STILL and it just sits there.

Once I seal it, I will photograph and display.

[ttthhh]

I sealed the end with a hot glue plug and ...

Just in case one of the newbies (like me...) is thinking about sealing BOTH ends of the cap with hot glue:

The heat of the hot glue can definitely detonate HMTD!

At least use a spacer (cotton) before closing the cap with hot glue. And wear gloves, glasses and ear protection...

[parabolic]

The method I have tried, is to use the sections of an antena whip aerial you get on a radio, you get a whole lot of different diameter segments to choose from in just one aerial., I then cut a piece off about 2 inches long, slide a close fitting drinking straw in, crimp one end with pliers, ( carefully so not to crack the tube because the meterial is slighty britle), I used slightly moist HMTD about 2 grams, gently tamped it in, put the bridge wire in and then used some quick setting metal epoxy to seal.

I left the det for about 3 days, then tried it out, I was behind a stone wall before I let the buggar off.. Sounded louder than my 308win, couldnt find any remains of the det apart from my bridge wire.

Id rather use dry HMTD and then wet it with acetone when I want to load a new det, but iam not sure what Acetone does to HMTD. so I havent tried.

Every time I make HMTD I cant get enough courage to load a det up, I get to scared incase something goes wrong and the darn thing goes off when iam loading it.

I end up just burning it or hiting small piles of it with a hammer, (with earmuffs) :)

Para

[k_illyrian]

well, as for the casing you could use the plumbing tubes we use in europe...
it's body is made from 3 layers (inner plastic ,midle Al, and outer plastic which can be stripped of if needed)
these pipes are tested to take the preassure of at least 10 bars, can be bent and are available from 1/4 to 3/4 inch diam...

[Bert]

Moderators:
Perhaps this whole thread should be moved to the "other explosives" section? HMTD and blasting caps aren't pyrotechnics by me-