pierro - 12-4-2013 at 06:11
Hello everyone, I post a new subject here because I have a problem when detonating RDX.
A made explosives for a few years (as a hobby) but never succeded to have a proper initiation of RDX.
I use a detonator homemade with 2 or 3gr of HMTD (the same than Ragnar Benson describe in his books) and works very well.
For the manufacture of RDX I use the classic process which involve the nitration of methenamine with nitric acid. I made myself the nitric acid by
distilation of sulfuric acid with KNO3 (without pump so there is some nitrogen dioxides in the final product). Despite the nitrogen dioxide in the
nitric acid I manage to have RDX cristals and when I run a burn test it burn exactly as RDX cristals (orange flame with a little whistle ) but for an
unknown reason it does not want to detonate with a blasting cap even in his cristals form (without plasticize the RDX).
I have some hypothesis : (maybe nitrogen dioxides prevents a good detonation but the RDX cristals looks ok at the end of the process, maybe my caps
are not strong enough but 3 gr of HMTD is quite strong...) but I really don't know where the problem could come from.
Could someone help me please ?
Thank you for your help (and sorry for my bad english ^^ )
Motherload - 12-4-2013 at 09:08
What quantity are you trying to detonate of RDX ?
Is it dry ?
Ral123 - 12-4-2013 at 09:36
RDX is the base for reliable detonators. Mine needed sub gram quantities of AP.
Did yours burn like that
http://www.youtube.com/watch?v=_O1MEyy3SPg
Even Tetryl needs very little AP. Are you sure your HMTD DDT's?
Peroksit - 12-4-2013 at 10:34
Try HDN to RDX maybe you are succesfull . you try with lead azide or diffirent primary explosives
[Edited on 12-4-2013 by gamez34]
Simbani - 12-4-2013 at 10:50
Do you have real crystals? If not, your product is likely to be HDN with only a small amount of RDX. Try recrystallizing your stuff in warm acetone
and filter the insoluble things out. HDN is insoluble in acetone or EtOH. If you throw hexamine into fuming nitric acid your first product will be
RDX, but
as time progresses the water content rises to the point where only HDN falls out.
But maybe it´s just your acid, if you distill it only one time and over normal pressure you won´t get over 90%.
Fantasma4500 - 12-4-2013 at 12:42
i guess you should try...
using water tamped focusing of blasting cap towards secondary charge
perhaps you could make this as in just burying it in the ground or putting it in a bucket of water (if it is succesful, even 3g HMTD will get the
bucket split by inifinite chances)
or perhaps as others suggested using another initiation? try ETN, if that doesnt work then theres something completely wrong (:
pierro - 13-4-2013 at 06:14
I have tried 25gr of RDX (twice) unsuccesfully. Yes I think it is dry and burn exactly as the burn test video on youtube.
Yes I am sure my HMTD detonate regarding the loud Boom on detonation (sounds like a heavy gunshot).
For the nitric acid I think it is over 90% because the reaction with copper is very slow at the beginning and only when I add water the reaction
become strong with lots of fumes.
Concerning the HDN I cristallize already with acetone (a mix of cold water, ice and acetone).
Maybe I'll try by changing a little the composition of my blasting caps for example by mixing HMTD with RDX to stronger the detonator (or even with
only RDX do you think it will detonate ?).
No matter what I will keep trying 
[Edited on 13-4-2013 by pierro]
Motherload - 13-4-2013 at 06:31
If the RDX is pressed too much ..... It will be really hard to detonate.
No more than 70-75% theoretical density.
Also what size tube are you loading the RDX in ?
IIRC ... RDX has a critical diameter of 4mm..
pierro - 18-5-2013 at 06:11
Ok, I've continued working on it and here are my results : I finally succeded to detonate it with a much stronger blasting cap (7cm lenght composed of
approx 1 gr of RDX and 2 gr of HMTD) I think it is stronger that any detonator should be but it works.
However I have some other points that I can improve : I have read that RDX must not leave any residue when it is burned and mine leave a little of a
sort of white paste. Maybe I think this can come from the fact that when doing my RDX I do not heat up the mixture nitric acid/hexamine between 50 to
55 degre after mixing nitric acid and hexamine (like classic process indicate) because if I do this it create a run off and uncontrolable situation
with lot of nitrogen gases. Instead I let the mixture heat up by itself by removing the beaker from the ice until it reach 30 degre approximately and
then I throw it into cold water and acetone. Do you think that not heating the mixture and cristalizing RDX from this temperature (at 30 degre rather
than 50) can decrease either the quality or sensitivity of RDX cristals ?
Thank you again for your help (and sorry for my bad english)
[Edited on 18-5-2013 by pierro]
Motherload - 18-5-2013 at 06:22
I will have to say that your methanamine/hexamine isn't pure..
Seems like some sort of a binder or something .... Which is probably your residue.
pierro - 18-5-2013 at 06:27
Ok, however I take my methenamine/hexamine from the fuel tablets named "esbit" I don't know if you know those tablets but I supposed it was pure
hexamine...
So, for you, don't heating up the mixture is not a problem ?
[Edited on 18-5-2013 by pierro]
Ral123 - 18-5-2013 at 06:33
I wonder if someone have made an explosive synth, with intent to obtain explosive material, but the material doesn't want to detonate, is this legal
In my opinion, RDX is the most reliable energetic in the homemade arsenal. Are you sure your HMTD is good? There were people on the forum with
extensive troubles getting their HMTD to detonate 
pierro - 20-5-2013 at 05:41
Ok thank you for your advises, but I think I will give up this expensive (and risky) hobby cause I don't have the funding (and the willing) anymore,
anyway thank to everybody for your help and good continuation to all.
[Edited on 20-5-2013 by pierro]
Hennig Brand - 23-5-2013 at 05:15
It was a long time ago since I tried making RDX, but I remember having the same problems you are having. The product was really difficult to detonate.
I used homemade hexamine made from formalin and ammonia, as well as homemade nitric acid for the synthesis. I distilled the HNO3 twice under
atmospheric conditions and used urea to get the NOx out of the acid at the end. I should have used dry air since the reaction with urea produces water
which dilutes the acid (I have since obtained the equipment and materials necessary to bubble dry air through the acid). I measured the density of my
acid, but after adding urea I am sure my acid was barely up to the task of producing RDX. I think the density of my acid corresponded to somewhere in
the mid 90's and that was before adding urea.
I also noticed that when I cleaned the crude product up well using recrystallization (water and acetone) that it detonated much easier. BTW, even on
the first recrystallization almost everything easily dissolved in warm acetone which indicates the impurity, whatever it is, was also soluble in
acetone. I noticed the crude produce, when recrystallized for the first time, did not come out in well formed crystals from warm acetone even though
almost everything dissolved in the acetone easily. I noticed after a couple more recrystallizations using acetone and water that the produce did come
out in well formed crystals which detonated much more easily. Even these well formed crystals were significantly harder to detonate than PETN however
(the sensitivity of RDX is of course known to be less than PETN). A significant amount of product weight was lost during purification.
I quickly lost interest with RDX for the most part. It requires ultra pure, highly concentrated acid and even then the yields are terrible compared to
PETN for instance. I mostly stick to solid nitric esters for caps now, because they are simple to produce in high yield and with minimal expense.
edit:
BTW, I used dilute HNO3 to first produce HDN.
[Edited on 23-5-2013 by Hennig Brand]