PVB stars.

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Pyro-Gear
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PVB stars.

Post by Pyro-Gear »

I have so far made a red/green/blue/yellow/ plus a white strobe, now something is jumping out PVB burns hot very hot! And what I find amazing that the oxidisers can be dramatically reduced, and that is taking me out of my comfort zone but I have working stars.

One other thing that has become apparent is the PVB can be reduced to as little as 2% and that’s knocking out the red gum and Dextrin in known formulas, the stuff is fascinating.
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Re: PVB stars.

Post by richardh08 »

My brief excursion into playing with blue formulations including PVB did seem to indicate that it burns hot.

If it takes you out of your comfort zone, what hope is there for the rest of us poor mortals?
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Re: PVB stars.

Post by sambo »

Ha ha - seconded !

I'm interested in looking at some glitters if that's at all helpful, or if there is anything else you'd like me to look at.
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Re: PVB stars.

Post by Pyro-Gear »

Tonight's star tests:

Green stunning.
Red a strong red awesome.
Yellow awesome great sizzle.
White strobe very good but a little too long on the burn time.
Blue intense blue to start but washes out, this is one that is going to bug me!
Purple a very nice star.
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Re: PVB stars.

Post by Lloyd »

Blue intense blue to start but washes out, this is one that is going to bug me!
---------
Ken,
I believe you mentioned that PVB fueled stars burn a little hotter than with other fuels. The symptom on the blue star seems (perhaps) that it's burning near the 'transition' temperature where the blue is damaged by being too hot. While flying fast, at the beginning of its flight, the higher air velocity could keep the flame envelope somewhat cooler, and when it slows and enjoys less airflow around the star, it burns hotter.

So, if it were my circus, I'd be altering the formula to make the entire burn a bit cooler, in order to avoid the transition to "too hot".

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Re: PVB stars.

Post by Pyro-Gear »

Lloyd i would say your absolutely right, I will have to rethink the blue today with the addition of copper carbonate, I should have the results in the next 5 hrs.
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Re: PVB stars.

Post by Pyro-Gear »

My initial results are looking very promising.

Completely omitting the Magnalium and introducing an amount of copper carbonate I have a working blue!

Now for the fun bit, I found I can control the burn rate by adjusting the amount of PVB 2% gives a slow burning blue around 6 seconds on a 12 X 12 pumped star 5% however gives me 4 seconds with no loss of colour on the same star size, air test tonight I will keep you posted!
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Re: PVB stars.

Post by Lloyd »

Completely omitting the Magnalium and introducing an amount of copper carbonate I have a working blue!
000000000
Hooray! BOTH served to lower the temperature. I'm really happy to hear that changing the fuel percentage will affect the burn rate that much.

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Re: PVB stars.

Post by Pyro-Gear »

I'm really happy to hear that changing the fuel percentage will affect the burn rate that much.

LLoyd[/quote]


It works very well :
More interesting stuff all the stars I have made to date have had an extremely low ignition point so I made some changes to the prime (as you do) just to see what I could get away with, firing the stars from a tube (as I do) I decided to try no prime just to see what would happen to my amazement they ignited.

But obviously we need the whole star to ignite uniformly in a shell, so I then used plain old BP with 2% silicone I had no issues at all.
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Re: PVB stars.

Post by Lloyd »

A friend is sending me a pound of the Eastman Butvar B-76 to test, also.

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Re: PVB stars.

Post by sambo »

Nice one Ken!
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Re: PVB stars.

Post by Pyro-Gear »

OK back to the stars, I have passed over the formulations to Richard and talking to him today he seemed very happy.

We should have some information up later from the data recovered from the spectrometer.
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Re: PVB stars.

Post by richardh08 »

Rain stopped play last night, so all I have so far are the results from my light box measurements on the red, yellow and green. Here they are:
KenPVB.png
Each rectangle contains colours representing the RGB data, adjusted in MS Paint to my 'standard' luminosity (134, for historical reasons). In each box the top colour is the average of all the readings I took (17 for the red, 16 for the green and 12 for the yellow) and the lower one is the individual best result in each case.

As always, the colours don't really do justice to the effect on the eye. So far, although I've only seen them close up, they look very good. The red and green have closely similar burn rates and the yellow is about 30% faster - it's one of Ken's specials, with a high magnalium content, and really sizzles!

When and if it stops raining for long enough I'll try and get some spectra.
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Re: PVB stars.

Post by richardh08 »

I've just realised I made a bit of a boo-boo while recording this data. I left the camera on auto white balance, which probably means the colours are degraded from their true values.

Ah well, I now have some spectral data, from which it ought to be possible to calculate chromaticity coordinates, and then reconstruct sRGB values. If that works, it will be interesting to compare the results with the direct photographic values.
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Re: PVB stars.

Post by Lloyd »

I cannot say who it is or what it's used for (besides "stars"), because I'm under a non-disclosure agreement with the firm, but I know now (finally) of at least one manufacturer of commercial goods using Butvar B-76 (out of Germany) as their binder!

This is good news, as they've been making the product for years with that binder system.

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Re: PVB stars.

Post by Tom Schroeder »

Lloyd wrote:I cannot say who it is or what it's used for (besides "stars"), because I'm under a non-disclosure agreement with the firm, but I know now (finally) of at least one manufacturer of commercial goods using Butvar B-76 (out of Germany) as their binder!

This is good news, as they've been making the product for years with that binder system.

LLoyd
I don't want anyone thinking there is any magic to B76 after you bought a boat load of the mowitol. :o

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Re: PVB stars.

Post by Lloyd »

No, Tom. That wasn't the implication. The issue is: There is at least one successful firm using PVB as a binder in stars. And, for some time.

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Re: PVB stars.

Post by Tom Schroeder »

Lloyd wrote:No, Tom. That wasn't the implication. The issue is: There is at least one successful firm using PVB as a binder in stars. And, for some time.

Lloyd

I figured that but you know how pyros can be, I didn't want anyone to think "Oh, s..t" we bought the wrong stuff.

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Re: PVB stars.

Post by Lloyd »

"...you know how pyros can be..."
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Heh! YEAH! Do I ever know that!

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Re: PVB stars.

Post by richardh08 »

I'm still waiting on the arrival of the latest PVB sample, but I'm guessing, from what I've seen and heard so far, that the variety will turn out to be largely irrelevant, both for colours and for crackle.

In the meantime, I now have some spectral measurements on Ken's three colour compositions with PVB.

The spectrometer alignment was not ideal for the red sample, which is a little truncated at the long wavelength end, but they give a reasonable idea of the emissions from all three mixes.
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Re: PVB stars.

Post by Pyro-Gear »

On the red possibly a slight strobe effect I have found ground tests to slightly indicate this effect.

Nice work Richard as always.
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Re: PVB stars.

Post by Pyro-Gear »

Lloyd wrote:I cannot say who it is or what it's used for (besides "stars"), because I'm under a non-disclosure agreement with the firm, but I know now (finally) of at least one manufacturer of commercial goods using Butvar B-76 (out of Germany) as their binder!

This is good news, as they've been making the product for years with that binder system.

LLoyd
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Re: PVB stars.

Post by richardh08 »

I've been thinking about the spectra, particularly about that fairly strong blue-green line in the plot for the red star. I've seen it in other red star spectra, but not that strong. The best measurement I've been able to get of its wavelength is 461 nm.

It turns out that there is a very strong neutral strontium line at a wavelength of 460.7 nm, so it looks likely that that's what I'm seeing. There are other, less strong lines in the range 515 to 525 nm, which more or less match the smaller emissions that I see in that wavelength range.

Assuming that they are from neutral Sr atoms, why should they be much stronger than what I've seen in other red formulations? The only reason I can think of is that the flame is sufficiently hot to dissociate at least some of one or more Sr compounds into their constituent atoms. A hot flame would also fit with the relatively large amount of continuum radiation that I see being emitted by these three stars.

Is the hot flame a consequence of the PVB content? To be reasonably sure, I guess I'd have to look at spectra from similar formulations with the PVB replaced by some other binder. However, this interpretation fits with the difficulty both Ken and I have found in trying to formulate a good blue that includes PVB.
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Re: PVB stars.

Post by Pyro-Gear »

Is the hot flame a consequence of the PVB content? To be reasonably sure, I guess I'd have to look at spectra from similar formulations with the PVB replaced by some other binder. However, this interpretation fits with the difficulty both Ken and I have found in trying to formulate a good blue that includes PVB.[/quote]

Yes I would say so, I air tested all three stars in anger last night in some rockets, 40 gram headers on the 15mm tool, they went high very high! I would say looking at the stars in the air these are world class, the yellow jets a little but I can work on that having said that the effect was amazing the red and green was stunning, all in all there good stars.
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Re: PVB stars.

Post by richardh08 »

I finally got to see the effect in the air this evening. I have to say I found the colours to be highly pleasing. The yellow was brilliant, in both senses of the word!
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Re: PVB stars.

Post by Pyro-Gear »

Testing a red strobe tonight and it’s looking good so far.
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Re: PVB stars.

Post by Pyro-Gear »

I have a working red strobe all be it a little slow more tweaks I think. :roll:
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Re: PVB stars.

Post by Lloyd »

I'd like to apologize for promises made then broken.
I acquired the two materials I didn't already have for both the crackle and pvb stars, and now find myself "pushed into a corner" by a client. I've been working 18/7 since about a month ago, and haven't had the opportunity to even clear off my pyro bench and start a project.

Sigh...
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Re: PVB stars.

Post by richardh08 »

That's life!

I'm in the happy position of not being dependent on anything external to my own interests. I appreciate that most people aren't that lucky.
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Re: PVB stars.

Post by SwedishParaCordNut »

Pyro-Gear wrote:I have so far made a red/green/blue/yellow/ plus a white strobe, now something is jumping out PVB burns hot very hot! And what I find amazing that the oxidisers can be dramatically reduced, and that is taking me out of my comfort zone but I have working stars.

One other thing that has become apparent is the PVB can be reduced to as little as 2% and that’s knocking out the red gum and Dextrin in known formulas, the stuff is fascinating.
Is the formulas still under development, or can they be made public now? I just wounder 'cause I'm looking for comps to make PVB bound strobe stars.
(sorry for my bad english, I´m from Sweden)
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Re: PVB stars.

Post by Pyro-Gear »

I have made two strobe compositions a red and a white, now first what strobe compositions are you working with I suspect AP?
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Re: PVB stars.

Post by SwedishParaCordNut »

Pyro-Gear wrote:I have made two strobe compositions a red and a white, now first what strobe compositions are you working with I suspect AP?
Yes, AP, Barium nitrate, Strontium nitrate and Potassium nitrate. :)
(sorry for my bad english, I´m from Sweden)
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Re: PVB stars.

Post by Pyro-Gear »

Not knowing what formulae you are using it’s a case of try it, sub 2% PVB for any other binder, if you let me know the nitrate compositions I can test it for you.
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Re: PVB stars.

Post by SwedishParaCordNut »

Pyro-Gear wrote:Not knowing what formulae you are using it’s a case of try it, sub 2% PVB for any other binder, if you let me know the nitrate compositions I can test it for you.
Ok, I´m going to try that! :)

Is it possible to get the red and white comps that you have made?
(sorry for my bad english, I´m from Sweden)
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Re: PVB stars.

Post by Starfire »

Hi I'm after a good green and white star comp
Using pvb.
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Re: PVB stars.

Post by Rob.L. »

Barium Chlorate/potassium Perchlorate star composition. % by weight.

BaClO3 58
KClO4 15
BaNO3 8
P.V.B. 8
P.V.C. 3
Parlon 8

Solvent: xylene 30, ethanol 60, water 10 (approx)

Pressed in an 8mm tube and extruded out to 10mm long.
I noticed the extruded mix seems to be pourous but leaves a hard off white star when dried
left to dry overnight followed by 2 or 3 hours in moderate heat. 30 centigrade ish.

Lights easily. burns smoothly. No prime.

Completely random mix based on the activity of the chemicals in other formulas.

Will time the burn and do video when it's dark.

I will be tweaking the comp in various directions and will update. Looks green in strong sunlight so should be reasonable. It leaves a small amount of hard black residue so may be oxidiser rich.

May replace the KClO4 with AP to see what happens.
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Re: PVB stars.

Post by Pyro-Gear »

Interesting Rob it would be good to see a night burn, try to get a reflection of the light emissions as most cameras white out, and with 8% PVB those stars will be burning seriously hot.

One thing I would say when using PVB as the main binder I would remove any water from the wetting solvent as PVB has this habit of locking in any water period, IPA is the way to go Rob.
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Re: PVB stars.

Post by Rob.L. »

Pyro-Gear wrote:Interesting Rob it would be good to see a night burn, try to get a reflection of the light emissions as most cameras white out, and with 8% PVB those stars will be burning seriously hot.

One thing I would say when using PVB as the main binder I would remove any water from the wetting solvent as PVB has this habit of locking in any water period, IPA is the way to go Rob.
O.k., I wasn't aware that PVB would do that. I only used ethanol because all my IPA was at the lock up.
Got it now along with N-pentane and N-butyl acetate.
The stars are very hard but sort of ductile as well. I could see these doing ok in a 2 inch shell you know!
When the xylene was added the organic component melted nicely and the alcohol/water made the whole lot into a sort of marzipan like stiff flakey paste. (like you would expect from an alcohol mixed with a petroleum derivative.

I know that toluene dissolves parlon very well (Non-thermoplastic line paint) and the porosity of the finished article would affect the burn time so there is a lot of work to do!
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Re: PVB stars.

Post by sambo »

Hi Rob,

I'm hoping this is helpful and not intended to be negatively critical at all.

as Ken says it's a little on the high side in terms of PVB content, was that deliberate ? Your ash residue is likely from the Parlon. I can't recall off the top of my head if xylenes is a solvent for Parlon, I suspect it is. Ken is of course completely correct about removing the water it would have no solvating role and would lock in.

what are you using as your fuel ?

Please don't substitue potassium perchlorate for Ammonium Perchlorate in that formula unless you want to blow yourself up :-0

can you see why ?

Remember, of all the oxidisers we typically use, Barium Chlorate is generally the most sensitive and potentially troublesome.

Sam.
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Re: PVB stars.

Post by Rob.L. »

Just done the test in the dark and will try to upload the video somewhere.

As the burn got going it was obvious that the green was getting a bit washed out a bit by the fierce burn so I am going to drop the PVB a bit, increase the PVC plus a small amount of charcoal possibly., drop the potassium perchlorate a bit and up the barium nitrate.

the total composition wieght was ten grams. which gives eight stars. Given the chlorate content I would not like to make a larger amount unless it was proved to be stable over time.
This is experimental and I would not be happy doing anything constructive with it at the moment.
Better to use a tried and tested formula for the real deal.

Yes Sam the formation of ammonium chlorate would be bad news indeed! If I were to do that it would be a very small experimental sample NOT pressing of stars, sub half gram kind of stuff. I should have made that clear. Also I did do a shock sensitivity test with the current formula and it seemed to be fairly resistant as this type of comp goes.

Overall I was quite pleased with the result and would ultimately like to see one in the air as tests on the ground are not the best representation. back to work for now!
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Re: PVB stars.

Post by sambo »

You have to be careful if you add metals to your formula also, specifically Al ( if you were trying to intensify the flame without whitening it ) - for the same reason.
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Re: PVB stars.

Post by Rob.L. »

Yes, Quite.

If metalized stars were on the menu It would probably be better to start again....without chlorates.

The chloropolymers are of interest at the moment along with, any other compatible fuel or binder.
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