-----Original Message-----
From: Hedley Jones
Sent: 06 June 2011 12:16 PM
To: tiaan
Subject: How to prepare horn for use as scales?
Hi Tiaan
Do you know how to prepare horn for use as scales?
Thanks
Hedley
On Mon, Jun 6, 2011 at 6:03 PM, <tiaan> wrote:
Hi Hedley
First thing to remember about horn is that it is a "thermoplastic", which
means that it goes soft when hot and can be shaped, i.e. flattened and
clamped and that it will hold that shape when it cools down in the clamps.
When it is reheated, it will return to the original shape (like it was on
the antelope's horn.
So, to work with horn you need a couple of tools and supplies:
Four pieces of MDF (medium density fibre board, a.k.a Supawood) or four
slabs of smooth steel, larger than size of the eventual flattened piece of
horn.
Two pieces of thick soft leather as large as the palates or the mdf to use
if you want to preserve the horn's texture.
Four to eight G-clamps
A pan, large enough to hold two pieces of horn which have been cut to
approximate handle length.
Linseed oil or olive oil or sunflower oil, enough to cover the pieces of
horn in the pan.
A piece of wood, or an asbestos cloth, in case of fire you put this over the
pan to kill the flames.
A gas stove or an electric hotplate.
Two pairs of pliers
A bandsaw or a cabinet maker's coping saw to cut the horn slabs.
To cut the horn you need a pair from the same animal. Horn is symmetrical,
what happens on the left, is mirrored on the right. Even on the inside. The
exception is buffalo and gnu bosses, which are a bit random, but the main
features are still the same.
Mark a slab on one horn, and mark the other slab at exactly the same spot on
the other.
Use you bandsaw and coping saw to cut these pieces out. (If the inner bone
is still in the horn, you can knock it out and have it resin impregnated.)
Heat enough oil to cover both pieces of horn, and immerse the horn in the
oil. Thick horn will take some time to heat up, thin horn goes quite fast.
Do not try and heat thick horn up fast, as the outside can get burnt while
the inside is still cold. Patience does pay off.
You will see bubbles rising to surface of the oil, this is due to the
moisture content of the horn steaming off. When this starts happening you
can start testing the pieces for flexibility. They should bend with relative
ease when gripped with the two pairs of pliers. (Use the pliers, hot oil
burns are not fun.) Another good indication of the right heat is when the
tiny fibres along the saw edge starts to turn brown and curl up.
As soon as this temp has been reached you can place one piece on a piece of
mdf, place the leather on the texture you want to preserve, place the other
piece of mdf (or steel on top, and clamp together using at least two
G-clamps to ensure that the whole piece is flat. Repeat with the other
piece.
This clamping process should happen quite fast as the horn will harden as
soon as it starts cooling down.
If you used wood or mdf the horn will take about two hours to cool down, and
it can then be released.
Two things can go wrong: 1. You clamped the horn at too low a temp and it
cracked, or 2. you heated it too much and it burned to crisp. Literally. (It
is a good experiment to drop a small piece of horn in the oil, and let it
cook, flexing it every now and then until the edges turn brown. Then keep on
heating until it becomes brittle. And extremely smelly, like burnt hair.
This will give you a good indication of the heating cycle and when to clamp.
Then, wipe the flattened horn with kerosene to get the oil off. Place the
matching slabs together, flat side inwards and put a rubber band over them.
Leave for at least 24 hours, as there will be some bending taking place,
Rather have this happen before you glue them onto a knife tang.
All grinding operations should be done COLD. If the flattened slab just
smells heat it will start moving back to the shape it was on the animal. You
can quench horn in water to cool it down while grinding. Touch the surface
you have been grinding with your finger to make sure it is cold before
grinding some more, as horn retains a lot of heat, even if dunked in cold
water.
Wipe the inside surface with acetone or MEK before gluing, and use a slow
setting epoxy, one that is slightly rubbery even at full cure. If you use
one of the epoxies that is glass hard at full cure you will have a comeback
with three years, as horn does not sit still, even when glued screwed and
pinned.
Please email me if you have any more questions! I will gladly help.
Regards
Tiaan
Hi Tiaan
Thank you for your comprehensive answer. Its nice to know that there are
knife makers out there who are willing to share their experience and help us
beginners with their knowledge.
I may be bugging you with loads of questions in the future!!
Thanks again
Hedley
