Binding visco fuse together ? What to use

[Svimmer]

Hi any tips on what i can coat visco fuse with ? Just so i know when the machine is ready. I see that some use clear glue and some use ping pong balls and acetone but i find that to be rather expensive in my country.

[Arthur]

Well it should be lacquer, it's usually green but I've seen other colours. The Chinese way is to draw the dry fuse through a trough of thick viscous green lacquer and wipe the excess off with an O ring gasket in an adjustable clamp.

 

For the lacquer you could use NC (or ping pong balls which are usually NOT NC) in acetone but other lacquers may work, things like yacht varnish, nail varnish, even white wood glue. Read this vid,

Visco starts at 4.40 to about 7.20

 

It's important that the lacquer is applied thickly enough to make the product slightly stiff and water resistant, BUT it's also important to apply little enough lacquer that it doesn't contribute to the burn. If the lacquer contributes much to the burn rate then the fuse can flash over on the outside much faster than you expect (PVA may even be good because it doesn't burn quickly).

 

Added

I think I could even work out how to modify a hot glue gun to coat just a skim of hot melt plastic over plain fuse.

Edited February 3, 2018 by Arthur

[Svimmer]

Also i did read somewhere that Good BP is not hot enough to make visco fuse ? But it should be ?

[Arthur]

My personal opinion (and only that!) is that fuse of all types has been a subject in development for all it's production time. There are several compounds and several coatings purportedly used for fuse using various coatings of lacquers and paints and in the case of Bickford Fuse tar of some sort was used for waterproofing. That tar could have come from coal gas production or crude oil refining. Once Bickford took out the Patents, others would want to make something similar but without infringing the Patent so other formulas and constructions would be made, they may have been better or less good than Bickford, and they may have been cheaper (or not)!

[Mumbles]

Also i did read somewhere that Good BP is not hot enough to make visco fuse ? But it should be ?

 

 

I don't know if I'd say this is true. Hot BP can absolutely be used to make a visco type of fuse. Most fuses do not use typical BP proportions though. Fuse powder is a fine grained material made with potassium nitrate, sulfur, and charcoal in slightly different proportions. Of the stuff I've seen, I'd guess it was -40 mesh or so. It's usually given a numerical grade, which is seconds per meter. The mixture, as far as I know, is similar to 75:15:10 but has some modifications. It generally has a little extra sulfur, and this value is varied to control the speed. More sulfur, generally means a somewhat slower burn. I've also heard conflicting information about the amount of nitrate. Some say it has a bit more nitrate to consume the string, some say it has less. Sulfur burning to SO2 does consume less KNO3 than charcoal at least, so it's probably a balancing act.

 

Sorry I can't give much in the way of concrete details or exact formulas, but hopefully it helped at least a little.

[UncleBeau]

have a container, like a large cc syringe (fat one)...... ') without the needle!

make a hole just big enough to pass your fuse thru it at the needle end, and fill the tube (container) with PVC cement and pull the fuse thru. That will water proof the fuse. Hang the wetted fuse vertically from one end and let dry