caul coating

[Jackpine Boyz]

building my first bow caul, it is adjustable made with 2x7 board with 3/4 plywood on each side.  this 3" wide form is anchored to 2 pieces 1/2" plywood glued together for squaring things up.

My question is how to protect it.  
I plan to do heat treats in the caul with some of my bends, and may do some steaming at times.

I was going to just put a water based sealer on it, but was wondering if there was a better product for the heat in particular as this would be more common than steaming on the form.  Shelac maybe?  Or would a thin piece of metal strip be better on  top of the form to reflect the heat?

Thanks
Clint

[PEARL DRUMS]

Don't out ANYTHING on it. You don't want dangerous fumes coming off every time you use it.

[scrub-buster]

I use 2x and 1x boards for my cauls.  I don't treat them with anything.  Will the heat affect the glue in your plywood?

[PEARL DRUMS]

Just the few knots in my 2x cauls fumes me out of the shop at times. The sap gets sizzling and smoking fast.

[Jackpine Boyz]

alright, ill leave them bare
i went with the plywood sides as I've heard of some people getting twists in the long boards.

next time ill just use 2 of the 2x to get 3 inch width

[KenH]

Caul?  I know three meanings for that word, none of which have anything to do with making bows.  From context I assume you mean the form or jig on which we build bows.

Caul (Oxford English Dicionary)
1  The amniotic membrane enclosing a fetus.

2 historical -- A woman's close-fitting indoor headdress or hairnet.

3 Anatomy -- The omentum.

[Jackpine Boyz]

Ken,
Interesting.
I've heard caul used as well as form, jig
Wonder how the word ended up with bow making/woodworking
I will stick with jig from now on.

Here was I was referring to.

caul
Noun
(plural cauls)

(historical) A style of close-fitting circular cap worn by women in the sixteenth century and later, often made of linen. [from 14th c.]
The thin membrane which covers the lower intestines; the omentum. [from 14th c.]
The amnion which encloses the foetus before birth, especially that part of it which sometimes shrouds a baby’s head at birth (traditionally considered to be good luck). [from 16th c.]
The surface of a press that makes contact with panel product, especially a removable plate or sheet.
(woodworking) A strip or block of wood used to distribute or direct clamping force.
(cooking) Caul fat.

[John Scifres]

Probably Torges' fault.  It's in "HOB" at least. He was always good with words.  Plus he was a cabinet and furniture maker so perhaps the word is more commonly used there.

I would not coat it.  I have a few cauls and I kinda like the burnt look to them after several year's use.

[mlsthmpsn]

In woodworking, clamping cauls are lengths of face-matched 2x boards with a slight curve on the interface surfaces... So that the high point is in the center in each.

When gluing up panels and other wide projects, the cauls go on top and bottom of the project so they overhang the edges. Then you clamp the ends of the cauls toward each other. Because of the curved, parallel faces the clamping force from the ends is forced along the entire length of the cauls... Making the panels stay flat and even.

They are ingeniously simple machines, and have all sorts of uses for getting clamping pressures where clamps cannot reach.