gluing in reflex with silk

[Julian]

I have a pure silk tie that I'll probably never wear. I want to use it as a decorative, yet functional backing on my maple paddle bow. It's 66" ntn, feels around #60 at 24" at the moment.

The bow has taken about half an inch of set tillering that I'd like to take out, and I've heard that this can be done with silk. Has anyone done this before? What's the process?

my plan at the moment is to clamp down my bow with 2" or so of reflex over the whole back, then stretch the silk tight and let it dry with the reflex clamped in. If it doesn't work I don't lose much but I'd like to hear peoples' thoughts.

[Julian]

actually, never mind.

a bit of set isnt a big deal and it'd be nice to keep in un-backed since the grain is so good.

[Badger]

  I don't think silk would hold any reflex unless it was about a 1/4" thick

[tattoo dave]

Silk will definitely not hold reflex. I love a silk backing though. It's great insurance. I've broke a couple bows that were silk backed, one with probably way too many knots, and was a questionable stave to begin with. It broke into three pieces, but the silk was still in one piece, which prevented the bow pieces from becoming projectiles.

And I agree, a little set is nothing to worry about.

Tattoo Dave

[TimBo]

I couldn't even see half an inch of set without my glasses!  I do like the idea of silk backing, and have a couple of ties set aside for that, but haven't quite found the right bow for it yet. 

[PatM]

A properly applied silk backing certainly will hold reflex. It's more complex than just gluing down a thin old tie though.
  Commercial silk backings were manufactured and applied with a stretching apparatus and were well documented for offsetting set.

[Badger]

  Commercially prepared is the key word here Pat, Under normal circumstances simply reflexing a bow and putting down a layer or two of silk will not hold reflex that is visibly measurable.

[PatM]

Did I not just say that?

 A person could still copy the commercial method, which is well documented.

[gfugal]

My question is how do you pre-stretch the silk. Unless you have thick commercial stuff, like previously mentioned, I don't see it doing much. I put reflex on this bow with a polyester cable which has about the same stiffness silk. It was pretty much low braced the opposite direction, then I tied the cable flat to the bow with string then glued it on and covered with another cloth backing. In the end, the cable just stretched some more, and I lost the reflex I induced and still got set. I do think it allowed for the wood to bend much further without breaking, but at what cost, since it staked and had poor efficieny?

[tattoo dave]

Pretty sure Julian specifically mentioned a silk tie...which won't hold reflex...Sounds like we are talking about two different backings here that both happen to be silk.

But I'd love to see the process of this commercial silk backing that will hold reflex. Can anyone do a build along?

Tattoo Dave

[PatM]

I'm just pointing that out because people seem to generalize that silk CAN'T hold reflex.  Usually accompanied by a Tim Baker quote that silk just keeps stretching.
    Silk strips were made esentially the same way unidirectional glass is made.  The strips were then clamped at each end and stretched and the bow back was glued and the bow laid on the tensioned strip and clamped until dry.

An old article in Popular Science described the process.

[DC]

That would be easy enough on a straight or deflexed bow but a good bit tougher on a reflexed bow. Wrap it with plastic wrap and rubber I guess.

[George Tsoukalas]

PatM is correct. It was done in the past according to TBB1.
I never had much luck doing it as a home bowyer but it was done.
 Jawge

[gfugal]

I'm just pointing that out because people seem to generalize that silk CAN'T hold reflex.  Usually accompanied by a Tim Baker quote that silk just keeps stretching.
    Silk strips were made essentially the same way unidirectional glass is made.  The strips were then clamped at each end and stretched and the bow back was glued and the bow laid on the tensioned strip and clamped until dry.

An old article in Popular Mechanics described the process.

I'm trying to figure how you clamp the silk on while also trying to pull the bow into reflex. I suppose you could heat-treat reflex into the bow first, but that won't stretch the silk. I can't imagine having enough hands to do it, using a stringer, step through method, or push-pull. Maybe if you had someone helping it's possible, or some kind of bracing peg-board. I imagine you would need at least two clamps per end to get enough friction to keep it from pulling out of the clamp, even then I'm worried it wouldn't hold on especially when you start wrapping it to get it to glued flat.

Do you happen to have a link to that article so I could see what they did? I'm intrigued. 

[PatM]

You're overthinking it.  The strip was clamped at each end between blocks of wood with sandpaper on them for grip  and then tightened with a mechanism like a turnbuckle at each end.  You only need to place a caul on the back(outside the backing strip) and clamp the bow to that if you want reflex.
 Tension on the strip doesn't mean you can't "bend" it.