An introduction to PVB.

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An introduction to PVB.

Post by Pyro-Gear »

Myself and Richard have been doing a lot of research on binders, one such binder that stood out is PVB.

I ran a series of tests on various formulations substituting Dextrin and red gum for PVB and I have had some remarkable results, these include far better colour, wider flame envelope and minimal residue.

The binder is best used with IPA although acetone can be used, the binder adds no chlorine but its fuel properties are interesting, heavy charcoal stars using IPA are dry in 24hrs with PVB.

Now it was not easy to source the PVB in small amounts but we managed to get 1 kilo for testing purposes and I must admit this will be my preferred binder in the future.

PVB as binder got to be a UK first.
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Re: An introduction to PVB.

Post by Tyvole »

Not easy to source eh? Apparently, it's often used as the inter-layer of laminated glass for windscreens. Not that I'm suggesting anything, of course... ;-)
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Re: An introduction to PVB.

Post by richardh08 »

Yes, all we need to do is to smash up our car windscreens and soak the pieces in a bucket of alcohol. I don't know why we didn't think of that. :shock:

To be serious, although Ken has run more trials than I have, I'm very impressed by the results I've seen so far. Dampening with IP alcohol - or 80:20 alcohol:water - gives a mix that pumps easily and cleanly, dries quickly and burns well. Adding a little more liquid until the mixture holds together makes for cut stars that are a dream to produce.
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Re: An introduction to PVB.

Post by Pyro-Gear »

I ran a test on a blue/green/red/yellow/ and a white strobe I have no complaints the stuff is awesome, I also ran a test rolling with PVB and again it was faultless beautiful spherical stars.

@ Tyvole yes it is used in windscreens and you can get PVB sheet no problem, but in a powder form it proved a little tricky but we have now links in to a supplier.

For me I will be using PVB without a doubt, I have developed some star formulations that I have tested, and I have passed on the information to another member who in due course will report back hopefully with some positive news.
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Re: An introduction to PVB.

Post by sambo »

Indeed I will be reporting back soon :D
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Re: An introduction to PVB.

Post by sambo »

Ok well I'm not exaggerating when I say this binder is revolutionary. I've just pumped some Hardt Silver tailed #3 :

KCLO4 32
BP 28
Al Dark 6
Al Bright 21
Al Flitters 5
Dextrin 8 ( Subbed for PVB in same quantity )

This is a very difficult star to consolidate normally ( not the high dextrin content ) and I normally have to pump under high pressure. With the PVB this was a complete dream. It's like using Parlon but without the nasty acetone or stringiness. I simply used 100% IPA, no need for boric acid (although you might add if storing), no Al nitrate reaction risk. Unbelievable.

I have several other ideas to try out and I'll post back on these tests too. I agree, this is rapidly looking like my binder of choice.
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Re: An introduction to PVB.

Post by Tyvole »

Sorry guys, I didn't want my levity to get in the way of serious technical discussion. That aside, this does seem to be a very promising development. I never really liked using acetone very much myself, somehow my dextrin bound stars never come out as hard as I would like, and red gum is, well, gummy. I know that each has it's own application, but adding another possible binder to the armoury has got to be welcome.
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Re: An introduction to PVB.

Post by biffo »

Can I ask if this came from your research into Chinese Dragon eggs or a different lead spured your interest? Thanks biffo
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Re: An introduction to PVB.

Post by Pyro-Gear »

Good question and yes we did attempt to use it for dragon eggs but unfortunately it did not provide enough confinement, what we did find though was that PVB is a revolution in star making the stuff is awesome, rolling cutting pumping stars are a dream.
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Re: An introduction to PVB.

Post by Starfire »

Will you be selling it PG.
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Re: An introduction to PVB.

Post by Pyro-Gear »

Yes, I will send you a sample to test.
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Re: An introduction to PVB.

Post by Starfire »

Thanks PG.
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Re: An introduction to PVB.

Post by Pyro-Gear »

I will put it in with your tubes there due to go out in the morning, I am playing catch up at the moment so much work on!
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Re: An introduction to PVB.

Post by biffo »

If you have a very small amount I could try I would be grateful , biffo
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Re: An introduction to PVB.

Post by Pyro-Gear »

Yes not a problem I have to send out your rocket tooling sorry for the wait blame that on royal mail that have lost 40 grub screws to pin the tooling! So I will put a little in for you to test.
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Re: An introduction to PVB.

Post by Lloyd »

Moving a bit...

I have an immensely experienced industrial chemist "at my disposal", as it were. I asked him about the Mowital 60H, and what equivalents there might be, in order to increase the availability of it.

First, he said that in 1/4KG orders, Mowital 60H runs about $4.00 USD per pound! That's wonderful! A group-buy would secure enough for almost limitless experimentation.

Next, he said about Butvar B-98:
------
"The Butvar B98 and Mowitol both have a residual hydroxyl value of 18-21 which makes them be less tolerant of dilution hydrocarbon solvents, less water resistant but more reactive with things like melamine.

Is there a crosslinking resin, hydrocarbon resin or aliphatic solvents in your formula?"
------

The reason for the last part of his question is that those ingredients will promote a cross-linking of the PVB with the other things, causing a "curing reaction" that results in a harder product than just dissolved-then-dried PVB would give.

Now, it turns out that Talas bookbinding supplies company sells the Butvar B-98 for about $19.50 USD per pound, making it reasonably affordable for experimentation. (and less for 5lb)

Solubility in isopropanol, ethanol, and n-propanol is universal among all the PVB variants.

Talas is a US company in New York, and likely ships non-hazmat worldwide. I'm certain there'd be British and EU bookbinders who also sell similar products. Ask them about the "residual hyroxyl value".

http://apps.bnt.com/ecom/catalog/produc ... ctID=17103

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Re: An introduction to PVB.

Post by helix »

I have PVB but its mowital B30H Im pretty sure. It has similar residual hydroxy levels to those you mention, Im curious about what can be used to crosslink this - do you know what crosslinkers work with this lloyd?

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Re: An introduction to PVB.

Post by Lloyd »

Jimmy, I don't. I'm an "empirical pyro chemist" (a shovel-full of this and a spoonful of that sort of fellow), but I will ask. The gentleman (and he truly is) is free with advice and willing to help.

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Re: An introduction to PVB.

Post by richardh08 »

Ah, the luxury of having the services of an experienced industrial chemist! Ken has experience of working with plastics, but most of what we learned came the hard way.

One of the things that led us toward PVB, and that particular variety, was the prospect of crosslinking, based on our findings regarding the behaviour of one or two proprietary pre-catalysed nc lacquers. In the end, that aspect turned out to be largely irrelevant. As of now, we suspect that the specific type may not be important but have no evidence regarding the behaviour of any other variety.

I probably shouldn't say any more for the moment.
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Re: An introduction to PVB.

Post by helix »

It looks like it can crosslink with phenolic resin amongst other things - presumably novalac.
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Re: An introduction to PVB.

Post by Lloyd »

I believe that's true. Also he alluded to the probability that any hydrocarbon resin OR an aliphatic solvent (like hexane or hexene) might do the trick. Benzene would not -- it's "aromatic", not aliphatic.

I'll ask. He's probably got the answer under his hat!

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Re: An introduction to PVB.

Post by sambo »

Well that's interesting. I do have a 1Kg sample of SharkPowderC2-400™ if anyone wants to try some. Obtained from this company in the Netherlands - see link. Now they told me it does cross link with phenolic and melamine as you say Lloyd and is specifically mentioned on this link. I'm also looking at plasticisers, I'm hoping someone can help me. I actually don't want to cross-link it but I want to make it ductile for extrusion into strands for another purpose. I understand for PVC something like Acetyl tributyl citrate might work ?

http://www.shark-solutions.com/?page=19&sub=23
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Re: An introduction to PVB.

Post by Lloyd »

I'll ask him about plasticizers, as well. But keep in mind that PVB, by its very nature, is VERY plastic and ductile. It's most-often the layer inside laminated safety glass for automobile windscreens.

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Re: An introduction to PVB.

Post by sambo »

Thanks, that would be really helpful. I have done several tests with PVB as-is but It's not quite where I need it.

If you email the company in the link above I'm sure they'd send you a kilo for free, probably even to the US. I explained what I was using it for and they were very accommodating.

Sam.
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Re: An introduction to PVB.

Post by helix »

Sam

I think ethylene glycol would work as a plasticiser for PVB. I recall it works for Phenolics.

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Re: An introduction to PVB.

Post by Lloyd »

Here's an initial response. It has some caveats.
--------
"i think we can get you to a system you can extrude if you can tolerate a few weeks of drying. what we do is plasticize with a slow drying solvent, adjust viscosity with high viscosity nitrocellulose and add a little micronized wax to get it to extrude clean and not stick together. It needs to be plastic to move through the extruder but the solids can't be so high that you are overloaded with resin solids."
------------

He's going to research it a bit more. In the meanwhile, this is probably a starting place.

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Re: An introduction to PVB.

Post by Lloyd »

Um... to add to that -- if you're intending to make an extrudable star comp using PVB as a binder, that's not the way to get the viscosity where you need it.

I have a fair deal of experience in extruding star compositions. It has mostly to do with a VERY CAREFUL use of solvents, in exactly the right amounts, and a lot of care concerning feed rates and cutting forces (as I assume the goal is to cut stars as they emerge from an extruder).

I built a LARGE 720-oriface, 20-litre star extruder for a client. It works a treat. Solvent/binder relationships are more important than almost anything else.

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Re: An introduction to PVB.

Post by Lloyd »

Nice one! You figured it out, if not to the molecule, then damned-near!

quote:
"You can plasticise (MY spelling!) PVB with diethylene glycol, triethylene glycol or brake fluid."
(end quote)

So... there you go!

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Re: An introduction to PVB.

Post by sambo »

Thanks all, I'll give this a try. I have also emailed the manufacturer for any other suggestions and will let you know.

I have 2 goals. One is, as you say, an extruder for making cut stars, I intend to adapt my hydraulic press for this purpose. The second is to use a small die to make a continuous strand a few mm in diameter which will function as non-brittle flexible fuse - this may be quite difficult.
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Re: An introduction to PVB.

Post by Pyro-Gear »

helix wrote:I have PVB but its mowital B30H Im pretty sure. It has similar residual hydroxy levels to those you mention, Im curious about what can be used to crosslink this - do you know what crosslinkers work with this lloyd?

Jimmy

you can cross link PVB no problem the big problems is you need a high temperature, cross linking is also dependent on the grade of PVB some grades have a higher acetalization of the OH groups.

So for experimentation purpose only take a small amount of PVB or phenolic resin an add a few drops of acetic acid 5% with water in other words vinegar and place in warm area you will note that it will start to cross link, in particular the reaction with the phenolic is interesting as the water molecules are driven out and what you have left is a hard plastic.

With the PVB being not water soluble you will get a hard chalk like substance but it will cross link, obviously acetic acid is not desirable as wetting agent in our game so if anyone can find a safe cross linking agent that will work at room temperature keep me informed. ;)
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Re: An introduction to PVB.

Post by dave321 »

Lloyd wrote:Um... to add to that -- if you're intending to make an extrudable star comp using PVB as a binder, that's not the way to get the viscosity where you need it.

I have a fair deal of experience in extruding star compositions. It has mostly to do with a VERY CAREFUL use of solvents, in exactly the right amounts, and a lot of care concerning feed rates and cutting forces (as I assume the goal is to cut stars as they emerge from an extruder).

I built a LARGE 720-oriface, 20-litre star extruder for a client. It works a treat. Solvent/binder relationships are more important than almost anything else.

Lloyd
this could actually be taken a stage further, if the extruded "cylinders" are chopped to a short length, they can then be spun at high speed on a herring bone profile circular plate, you then end up with a potential spherical star.

this process is routinely used in the pharmaceutical industry, and is called spheronisation to produce the small beads that go into capsule shells, the rounding off phase is called marumisation.......check out the caleva site here in the uk (I was a pharmaceutical scientist for 31yrs with Pfizer ltd)

http://www.caleva.com/spheronizer_mbs_120.htm

as Lloyd says the wet mass has to have some plasticity for good extrusion and sheronisation
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Re: An introduction to PVB.

Post by Pyro-Gear »

sambo wrote:Thanks all, I'll give this a try. I have also emailed the manufacturer for any other suggestions and will let you know.

The second is to use a small die to make a continuous strand a few mm in diameter which will function as non-brittle flexible fuse - this may be quite difficult.

Sam save yourself the hassle just buy some 3D printing cable all the work is done all you got to do is coat it.
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Re: An introduction to PVB.

Post by Lloyd »

FWIW, "solid fuses" (those without any sort of shield or overwrap) tend not to work very well in adverse wind or mechanical situations.

The most common solid fuse today (besides black match, discussed below) is Mantitor ignitor cord (once, instead, it was "Thermalite" cord). Both have a means of continuing the heat transfer in the event that a break or "blow out" of the solid composition occurs.

Both use at least one internal metal wire, which heats, glows, and guarantees transfer across cracks in the 'grain'. Mantitor Ignitor also uses a PVC outer sheath, which contains and shields the fire from the environment. The flame front is always a large fraction of an inch ahead of where the sheath finally burns away.

Your best example of an unshielded fuse is common black match. If damaged, and if burnt "in the open", it will often stall, at least until the cotton's glow moves the fire to the next area with powder on it -- but it sometimes just goes out! Yet, in contrast, if you encase black match in a "pipe" of some sort (be it paper, or the gallery in a rocket motor), then it burns reliably, no matter any small damage to it.

I'd say it's not a productive effort to try to produce a continuous rubber fuse, unless you also intend to overwrap it with something.

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Re: An introduction to PVB.

Post by Pyro-Gear »

I am not sure of what Sam’s game plan is to be honest but if he wants a filament then 3D printer wire should fit the bill.

Mantitor ignitor cord or PIC or Wassag dose indeed run a copper wire although I believe the manufactures for this type of cord has shifted to Portugal: http://www.rastilhosm.com/English/prodFuse.php# until we know what his intentions are I can’t comment no further.
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Re: An introduction to PVB.

Post by sambo »

Well it is a lot of hassle and I could save myself the bother but then you could have said that about heavy metal-less microstars ;) I don't really care if it doesn't work or go anywhere but doesn't mean it's not worth doing.

Actually the inspiration come from the thread on passfire that Lloyd started on PVB in which you posted a link to this badly translated patent : https://www.google.com/patents/DE434372 ... s-Ch0IVwB-

It discusses "strobing" due to different concentrations of PVB in layers of the composition. The idea was to extrude a fine cord of composition for the core and coat this simultaneously in an outer sheath, again composed of PVB in a different concentration / formula to make
a) strobing fuse
b) a new kind of all-in-one extruded fuse.

All the information so far is very helpful, thank you. I heard back from the manufacturers today and they use Triethylene Glycol, I have the info on that if anyone is interested.

I actually really like the spheronisation / marumisation idea for the extruded stars so I will look at that.

Sam.
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Re: An introduction to PVB.

Post by sambo »

Just putting this down again - In terms of extruding for stars I'm really saying I think star making in the hobby could be what WASPing is for pasting if it was thought about enough, now that we have PVB.
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Re: An introduction to PVB.

Post by Lloyd »

Sam,
Star extruders/cutoff devices are nothing new; not in the industry nor in the hobby.

Not only 'rubber' stars, but most any composition can be extruded and cut in a more-or-less continuous process, and many hobbyists have done it, by dint of hydraulics or mechanics.

My commercial design does not use a continuous feed, but a calibrated 'pulsed' feed that first extrudes, then allows the knife to cleave the stars from the extrusion plate into a slowly rotating vessel of dry priming composition. Then it advances another increment.

It uses a lead screw and a reciprocating drive with a one-way clutch, rather than continuous pressure on the extrusion cylinder. The advance actuator moves to extrude then retracts (to relieve pressure so the extruder plate does not "ooze"), waits for the knife, then repeats.

"No secrets". It's the physical implementation that's proprietary, not the principles.

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Re: An introduction to PVB.

Post by sambo »

Very interesting, I know i'm highly unlikely to come up with anything that hasn't been done before or hasn't been done better. The method you describe makes total sense. To be honest, my plan once having got a suitable consistency and strand formed was to hash together an adapted 3d printer and use this - do you know if that has been done ?
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Re: An introduction to PVB.

Post by Lloyd »

No... I can honestly attest that I've never heard of extruding stars with a 3D printer!

Given that the 'strand' will be solidified and not particularly heat-labile (nor TOLERANT of much heat), how, exactly, did you plan to re-liquify it for 3D printing? Or were you just counting on the printer to advance the strand so it might be cut-up? (If that's the case, I can think of simpler methods. Think "automated fuse cutter".)

I'd add that such strands are bound together, yes, but exquisitely delicate mechanically. You can't introduce enough PVB into a formula to make a truly 'rubbery' strand, and still get it to burn like a star.

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Re: An introduction to PVB.

Post by Pyro-Gear »

Well this subject is going way off the original post regarding PVB I personally can’t see how a 3D printer is going to make a star:
Just to reiterate I suggested a 3D printer filament to save time trying to extrude PVB just to add if you want to extrude PVB you may well be looking at some serious money you would need to construct at least a 5 stage extruder feed/ pump/compression/pump/feed then out the die in to water bath.

Just to add the barrel would need heating jackets no solvents! Oh and a vent at the feed phase.

Back to reality: I have now sorted the final colour system using PVB I have the blue as good as it gets and some dam good strobes to boot as soon as I have finished my data base I will putting this forward to AFN for vetting.
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Re: An introduction to PVB.

Post by Lloyd »

Hmmmm.... post disappeared??

Ken... did the blue get significantly better by adjusting the metal or adding a heat-sink?

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Re: An introduction to PVB.

Post by Pyro-Gear »

Lloyd with the addition of the PVB in place of the dextrin the results were pants, I have removed the red gum and Dextrin and subbed that for 4% PVB colour is good and a vast improvement over the original test, I have now tested the star without any metals and boy it looks good burn rate is a little slow so I may up the PVB to 6-8%, blue is the only colour to give me any problems to date, the stuff burns hot and clean.
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Re: An introduction to PVB.

Post by Lloyd »

Heh! I had to look up the use of "pants" in the British Urban Dictionary! <G>

I don't recall the original formula. If there were both aluminum and Mg/Al in there, I'd suggest adding back just the tiniest bit of Mg/Al (but NO Al). It has little effect of whitening, but can dramatically speed up a comp.

But, perhaps only some additional PVB will do the trick, and that would be the more-desirable way. If you pass the point of becoming fuel-rich, you'll start to contaminate the flame envelope with incandescent carbon particles, trending toward yellowish.

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Re: An introduction to PVB.

Post by Pyro-Gear »

Ah sorry my terminology for MG/AL is magnalium: as you have found out pants is basically crap.

Original formula:
Blue:
Potassium perchlorate 49%
Hexamine 4%
Copper (II) oxide 16%
Parlon 12%
Red gum 8%
MG/AL 4%
CMC or Dextrin 3%

So now I have knocked out the red gum and dextrin plus the magnalium and subbed that with 6% PVB now we need to do a test with the spectrometer but to the eye it looks pretty good so far.
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Re: An introduction to PVB.

Post by Lloyd »

Ah! Just found from my materials guy that Castor Oil is an effective plasticiser for PVB, and can be used up to 30% w/w with it. It is also a good deal less fugitive than ethylene glycol, so might contribute to longer life of stars made with it.

I'll add that I personally know Castor Oil to polymerise in the presence of certain oxidizers, so it might end up being a "curative", as well.

Plus... you can buy it at your local chemist's shop!

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Re: An introduction to PVB.

Post by Pyro-Gear »

Interesting I was given castor oil by the spoon full back in the 60’s:

I am not sure if I would want to add anything as plasticiser to PVB its fine as it, polymerisation with an oxidiser is interesting, so I assume the addition of castor would aid to homogenise the melt? That’s if you should want to extrude it.

Ok I ran a test some time back with a red star I made I would say it has to be around 6 months ago PVB was at 7% in the mix the stars were pumped 12mm wetted with IPA and air dried for 24hrs I then placed the stars in a bath of water for 30 minutes I then pat dried them with a kitchen towel and they ignited no problem, another test I made was to make an AP based star with PVB and primed with a nitrate based prime 6 weeks down the line no issues but I would not recommend a test until my final results are written.
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Re: An introduction to PVB.

Post by Lloyd »

The ability of a resin binder to COAT as well as bind the components of a mixture is important to moisture-resistance; especially-so when using hygroscopic nitrates as oxidizers.

We made "lightning comets" (super-fast-burning) effects for stage. For those (which contained in some, strontium nitrate of unknown provenance), we bound with a solution of parlon in certain hydrocarbon solvents. The 'waterproofing' effect was profound.

As you saw with yours, the stars could be immersed in water for a time, then dried-off, and they functioned properly.

As an aside to this, we also use pharmaceutical tablet presses to make stars compressed to tens of Kpsi. Those, too -without ANY special treatment- are nearly completely waterproof. They are not made with any liquid resins at all, but pressed completely dry. Apparently, substances like red gum and parlon/saran tend to momentarily liquify and spread throughout the comp under those extreme pressures, much like ice melts under mechanical pressure (think Ice Skates).

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Re: An introduction to PVB.

Post by sambo »

Lloyd, thanks again for your help, you have gone out of your way. It is appreciated very much is all I can say. The addition of a plasticiser is certainly relevant, regardless of extruding, as when pressing stars with some metals sometimes it becomes very messy and quite awkward. In that sense PVB may not be the most ideal binder for all pressing purposes. I disagree with Ken that it will replace all other binders.

In the interests of keeping this on-topic i won't clutter this thread any further with my plans. I will say I welcome constructive feedback, negative and positive, and open discussion but i do not welcome unnecessarily critical, dismissive and supercilious comments; and I'm afraid Ken that is put to you.

Thanks again.
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Pyro-Gear
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Re: An introduction to PVB.

Post by Pyro-Gear »

So this is a little like sulphur becoming elastic under pressure a molecular entanglement of the carbon and nitrate for BP pucks: you have me thinking Lloyd seriously.
Ken.
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Lloyd
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Re: An introduction to PVB.

Post by Lloyd »

You got it, Ken!

Sam, Nah, that's not "out of my way"! This is what I DO for a living! It's fun, too.

Although I do it commercially, I've never lost my love for fireworks (and hopefully never will!).

But thanks for the compliment.
L
"Pyro for Fun and Profit for More Than Sixty Years"
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