Somebody experienced this before?

It looks to me to be the natural splits and cracks of the horn have continued into the prepared surface. When I prepared horn strips, I noticed that these natural cracks went quite deeply into the horn and for that reason I think it is best to get the largest horn even for narrow strips.

Well, that could have been it! Just prepared a new horn strip for replacement and noticed several very short fissures that go sideways into the horn. When the limbs are bent they probably extend further inside...

Thanks for your help!

JJ

If you bought this horn from Dick Gmbh, let it be, cause he don?t know what hornbowyers need.

Michael

Sawed the strip out of a philippine buffalo horn. Maybe too small, that one ;-) Tried another one and it seems better now!

Hi JJ,

In your horn do you have lots of grooves? Natural ones from the horn. I have that in my horns but I think if i sand them down I will still have plenty of horn left :) I have two asian water buffalo horns both are 70cm long.

Rebel, of course there are a lot of grooves in the horn :evil: .

I?ve got some quite small buffalo horns and it?s not easy to prepare proper horn strips... (Got a few bigger ones , too, but save them for later bows ;-)

JJ

Guess I figured it out finally after making several horn strips that all developped cracks...

Use of the heat fan for straightening the strips obviously dries out the horn too much and it gets brittle. Purposely I overheated a small part of a good, fexible horn strip till it became yellow. After cooling it developped cracks at this spot after minimal bending. So I guess excessive dry heat destroys the structure of the horn.

Or does somebody know a way to make overly heated horn flexible again (watering, oiling etc.)???

JJ

Does'nt the cells collapse like in tree? I've just read "the kiln drying" discussion in TBB vol. I. Just at though.

I think if that is a possibility, then there's nothing left?

Hi JJ,

if the horn went into yellow by heating, you burned it! You have to remove the yellow area by scraping it, until the healthy (black or dark-brown) horn apears again.

The savest way, to straight a horn strip, is to put it 10 - 15 minutes into boiling water and then clamp it, with the outer side, on a slight concav form. After cooling down, the strip should be straight.
Horn has a "memory". If you heat it again, it goes back into its natural form.

Petr

Well I?ve come to the conclusion that even when you scrape away the burnt horn, the area under it becomes brittle and develops cracks when bent! So I guess the heat gun is not suitable for hornbowmaking ;-) I ruined two strips this way. Another had a crack from the beginng...

I have already straightened another strip of horn by boiling and it seems ok. Takes some more time of course....

Just begun sizing the horn and the wooden core with fish bladder glue now. It was amazing how difficult it was to remove the belly horn from the bow before!


JJ

I didn't flatten my horn strips. Is this really necessary? The natural shape is a reflex curve.

Well, I don?t have so much reflex in the bow. And isn?t it definitely better for thinning on the belt grinder ;-)

How do you work them to their final thickness, Orda Khan?

JJ

Dr. Grayson is talking about this in TBB vol. II, p.144. You can overcook, and this leaves "... little by the brittle bone ...". ?t's the callogen who's important, and disappears. Not like kiln drying, ... but maybe the same effect.

Hi Juergen

Reading, Hein and Kloppsteg, the Turks used to boil the horns (strips) and press them into molds after cutting off the inner curves for further usage.

At the very beginning I also boiled the strips for hours and then they became very flexible and I could bend them flat. Now I am using a hot air gun but I never overheated (burned) neither the inner nor the outer surface. So far never any problem occurred.

But I experienced also some cracks with horns you got them from. Now I am waiting for a replacement. Luckily I saw the cracks before I glued the horn onto the core. The major difference was, the cracks were always lengthwise.

Could it be, because of the pressure while gluing the horn onto the core and how about thickness, 5mm or less? Another thing might be, the are too old or because of the storage (dry).

Best regards
Reto

hoi reto!


I have the feeling that too much dry heat makes the horn brittle so I decided not to use the hot air gun for horn bending anymore. I think its safer.

If the strips are thin they don?t have to be boiled that long. One hour seems to be sufficient. The horn becomes rubbery and can be bent very good.

Have some cornus siyahs in the pot right now I?m curious how easy this wood is to bend. It?s not cornelian cherry, but the dogwood which is quite common in Germany?s forests and parks. Didn?t turkish bowyers use Cornelian cherry for the siyahs? Or the handle only?

JJ

I am of the opinion that heat is not the problem as I have done some pretty severe heating to good horn without damaging it. I have boiled horn but also have heated it directly over low flame. Some horns are damaged by males fighting and worrying their horns against objects like fences, Poor diet sometimes affects wild animal horns.

Another problem is that if you are straightening the horn for string lay, that bend is almost certain to return in the finished bow to drive you crazy. Not only does heat make the horn return to its original bend but adding moisture (sinewing) has the same effect.

You do not see the Koreans straightening horns for this reason.

Many bow making cultures other than the Turks used multiple strips of horn. In this way one can balance curved strips against eachother using almost the entire horn, edges, inside curve and all. -j-

Another importent think is - from what climate in asia are horns. I know , its mostly impossible. Korean bopwyears select his horns from not very hot tropical -gentle climat in China. Tropical and subtropical climate horns has more grooves and unbalanced material thickness - and often crac.

JJ wrote:

How do you work them to their final thickness, Orda Khan?

I worked them down to the point where I could clamp them flat while I sanded them by hand. The finished horn strips were 4 mm along a shallow reflex arc.

currenly I am working on a new horn bow - again

I thought I got some good horns from the Ph, and now I discovered this....

- I used the hot air gun, but didn't burn it at all over overheated it
- I didn't discover the cracks before, or maybe I didn't flatten the horn that much, otherwise I would have discovered them earlier...
-

Those cracks happen, whatever the reason may be.

A simple trick to become aware of very small cracks is to moisten the horns sanded surface after having planed it. The surface dries very quickly, but where a crack is, the drying lasts much longer.
Globalisation serves us very qickly with whatever we want. But the old hornbowyers are even told to observe very closely the animals their horns they want for to make a good choice.

Michael

Reto, these cracks look as if they were already in the horn before you started working it. I?m having the same problems with Horn from the philippines that a friend gave me lately. These are so small that it is impossible to avoid the cracks. I have other strips that I?ve got from P. Cua, these are bigger and seem to be better quality...

Michael, that seems to be a very good method for detecting of cracks!

JJ

Did you bend horn before you glue it on bow? Maybe it cracked because that.