Butyrate "tauntening" Dope?

[Soarmaster]

I'm thinking someone on this forum might know. I'm considering building a replica of Octave Chanute's 1896 glider. So I'm testing coatings on frames of light cotton muslin. Chanute used "pyroxylene" and I have his formula -- and it's an outright Explosive! The modern egual would be nitro-cellulose dope (it must shrink and tighten the fabric). Well I wanted to avoid the nitro-cellulose and I purchased the minimal amount of butyrate "tauntening" dope. I've discovered that this stuff doesn't actually taunten any fabric I've tried. The coated fabric ends up more slack than before it was applied. This is Randolph Products 9701 "tauntening" butyrate dope.
Can anyone explain the "tauntening" label on this product? What am I missing?

[FlyingRon]

What fabric are you using? Tautening dope is for cotten/linen/silk. Even then there's more to it than just slapping some dope on the fabric.

[Soarmaster]

I'm using a light 100% cotton muslin(a type of weave). This is the same fabric as the original 1896 machine. I thinned the butyrate 1:1 with the correct thinner as per the directions on the Randolph products can. There is no taunting effect at all. Multiple coats have no effect. Does this stuff taunten only when used on top of nitro-cellulose dope?

[CHICAGORANDY]

IMHO if you have not already I would contact the good folks at Aircraft Spruce -877-477-7823 or https://www.aircraftspruce.com/contactus.php and get their advice.

[Airmutt]

Grade A cotton has not been manufactured for decades. It was known to have a shelf life and if improperly stored (exposed to humidity) it will never shrink and remain taut.

Butyrate dope should shrink cotton but butyrate dope with plasticizers is known as finishing dope and is non-tautening.

ACS has a good article by the late Ron Alexander on fabric. Here’s an excerpt…..
Most of the antique airplanes we will encounter were originally covered using grade A cotton fabric along with nitrate and butyrate dopes. Covering early airplanes with fabric required more work and skill than the processes that are available today. Grade A cotton was sewn in place on the airframe and then shrunk with water, which gave the cotton a moderate amount of tautness. Then several coats of clear nitrate were brushed on to fill the fabric's weave. As each coat of nitrate dope dried it shrank, pulling the fabric tighter. In other words, the shrinking dope continued to tighten the fabric.