velum for crack repairs

[John Cadd]

In a Strad magazine a few years ago I read about cracks being held together with small discs of VELUM,instead of wood patches.Is that what banjo tops are made of?
Has it been used for guitars at all?

[Paul Hostetter]

Vellum (two l's) is indeed a term for the kind of rawhide used on banjos and drums. And old-fashioned diplomas. It's an interesting idea, but not a very good one. Calfskin (or epidermis of whatever animal source) is of somewhat questionable structural integrity. Sometimes it's great, sometimes not. Considering it has to ride the rollercoaster of temperature and humidity changes, and assuming it is applied with hide glue as an adhesive, you have to recognize it has some inherent shortcomings. Which is why you really don't ever see it being used. A mention in The Strad does not mean it has a credible track record as a repair material. I have seen it as loose pieces rattling around the insides of cellos and basses: the wood itself changed shape, the skin changed shape, the glue got old and crystallized and lost its poop, and the patches simply fell off.

I have fairly much abandoned cleats and reinforcements of any kind on crack repairs because, after over 40+ years in the repair biz, I don't see any of them surviving very well. Usually I just glue the crack shut - period. If you;re the first person to do this, it usually works great.

What I have had much better luck with, in instances where some reinforcement is advised, is either silk (an incredibly strong material, way beyond wood or animal skin or linen or canvas) which I apply to the insides on instruments, or Tyvek, which I have only been using for about ten years. No failures yet, and some really intense field trials to help me evaluate. Tyvek is that stuff the USPO makes their bombproof Priority Mail envelopes out of. You can't tear it. But, believe it or not, the manufacturers specifically say it bonds best with hot hide glue. So I have reinforced top cracks in guitars with it and it seems to be doing fabulously well. I'd never waste time with animal skin. I already know how well it doesn't work.

[Magnus Hultin]

Paul, any advice on where to find this "Tyvek" material?
It sound like something worth testing..
How do You apply it? Paint on the hot glue first and then pad the material on with your fingers?

/Magnus

[Antonio Cotichini]

Interesting, Paul. I do agree about silk vs. canvas and linen. Never heard before about Tyvek (no USPO here in Italy!).
Where else one can find some samples?
Antonio

[Tim Mace]

Tyvek is used as close off material for building projects and signs(banner material)shouldn't be hard to find even as scraps from building sites or signshops.Very durable stuff but i wouln't make a banjo head out of it! or would I ????

[William F.Eden]

Paul is that not the stuff they sell for house wrap???????? Bill.""""""""

[Paul Hostetter]

It's the same as house wrap (it is a brand name and they really let you know it when you see a building wrapped in it!) and hazmat suits. Not only that, it's also the material that Remo somehow laminates to mylar to make Fiberskyn banjo and drum heads. Read all about it here on Wikipedia.

The mailing envelope stuff is a good thickness for instrument repairs. I'm sure you can buy it, but one used mailing envelope is more than enough for a lot of crack reinforcement.

[Tim Smith]

There is a synthetic in the Tyvek/Nomex family being sold as "Yellowstone" by a fellow over at Banjo Hangout. There is a long, long thread about it. I've used it for several banjo heads and think it is excellent. Very close to the skin head sound without humidity response. It is some what difficult to mount due to the stiffness - think of mounting a skin head without wetting it.

I have not used it for crack repairs. Most glues do not stick to it at all.

Tim Smith

[John Cadd]

Paul Brilliant answer .I never used this myself but love the idea of silk or Tyvek.A lot of people will benefit from your reply.Can`t help feeling sorry for that violin player when it all lets go.