To be honest, I only tried the 30H in our old, published PVB-based crackle composition, when I didn't find any difference from the 60H. I haven't experimented with it in any other circumstance. Maybe I should. I'll have to dig out my sample from wherever I put it!
I was curious about as the polyvinyl alcohol in the 30 and 60 is 18-21. With the 60H having a viscosity of 160-260 and the 30H being 35-60.
The 30T and 60T move up to 24-27 Polyvinyl Alcohol while barely changing the viscosity.
The 16H has a viscosity of 14-20 while having the same PA as the H's. So my simple mind thinks it would mix easier and better if the binding properties hold up. I did wonder if the lack of viscosity might lower the quality of rolling y'all had been seeing though is where we began to discuss of being tacky.
Then if the PA is a good characteristic the 30T might be a good choice between the two characteristics.
I think I missed the return call from sales while getting off the phone with Lloyd so I have till next week to try to figure it out. If I'm gonna purchase in bulk I wanna make the best choice I can from the resources available. I wouldn't feel right thinning a supply to upgrade and would have to eat it if that were the case.
My point wasn't to be flippant, but to try to emphasize that there's a difference between 'viscosity' and "tackiness"... although I do not know the 'official' technical term for the latter.
Still... I know that EXTREMELY viscous materials with 'low tack' will _eventually_ flow, while extremely tacky materials of even lesser viscosity might never 'drip out' of contact with a surface.
LLoyd
"Pyro for Fun and Profit for More Than Sixty Years"
Lloyd, the way I see it "tackiness" is synonymous with adhesivity. Adhesivity is dependent upon the 2 surfaces which are in contact with each other. My terminology may not be correct.
I have generally found binders, in the main, have the greatest utility if they exhibit high adhesivity to itself (cohesive) vs low adhesivity to the surfaces in which it is mixed and processed. Ixan exhibits this property.
The viscosity can be modified by the amount of binder / dry solids vs solvent and to a degree so can the adhesivity but not so much and not with the same relationship.
Parlon for example shows high adhesivity to many services including stainless steel and the adhesivity increases to a point as the viscosity lowers - commonly called "a sticky mess of parlon". With PVB the rate of change in adhesivity is less with increased solvent than with Parlon. Ixan even less so - you can add a lot of solvent and it holds itself together without adhering to smooth surfaces ( stainless steel ). So I think cohesivity (binding) is of greater advantage than adhesivity (sticking).
As for 30H vs 60H I have no idea at all, I'm not even sure what grade my recycled PVB is - perhaps I should dig it out and give it a try. Let us know Boo, I would be interested to know too.
Kuraray is being a little secretive with that information from what I had seen in there data sheets with all materials being 1-4 percent except one being lower.
Is there a question, here? Both the 30H and 60H are going to be perfectly acceptable as a binder for fireworks. At the same level of solids in a star formula, once the star is dry you will not see an observable difference. The viscosity, impact resistance and tack of the 60H would be higher due to the higher molecular weight. But in their patent Silberhutte used a nitrocellulose solution to reduce the tack, improve the rolling properties, improve solvent release and reduce drying cycles.
For armatures I believe this level of sophistication really isn't necessary. We are not trying to control coating weights as tight as the Japanese do in their ghost shells. I believe there is a whole level of sophistication the Japanese have developed that is unknown in the west.
Although I don't have much in the way of concrete evidence, I think Tom is right.
PVB is very 'tacky', regardless of its grade and viscosity, and I suspect that is the main reason for it being such a good binder (it is also the reason why our PVB-based crackle formulations tend to be a pain to granulate).
I doubt that the small differences in chemical make-up between the various grades will have any noticeable effect on the way that PVB-containing compositions perform.