Bleaching Horn

A few weeks ago I put two black buffalo horn scales in a plastic bag with some hydrogen peroxide. One of the two scales is now a dark reddish amber color. The other is still nearly black, with only thin fringes of lighter coloration along the edge of the hinge-pin end.

Has anybody else tried this before? Does anybody know why one scale is having a stronger reaction to the hydrogen peroxide than the other? As progress seems to have halted on the darker scale, I am open to other methods of bleaching the scales.

Thanks.

Bleaching dark horn is a bit problematical - at best you can lighten the colour or make it a reddish/amber colour. The old recipes involved caustic soda, red lead and nitic acid, and had a pretty deleterious effect on the horn.

I suspect that the reason one horn has responded better than the other is because they were not similar in composition in the first place. It might be due to fatty deposits in the horn which resist the bleach - they used to remove this with caustic soda.

When horn scales were predominant, I suspect that it was more a case of mixing and matching from a large amount of pressed horn plates to get a similarly graded pair.

Hydrogen peroxide was used a lot to whiten bone and ivory by the way, but you don't often find mention of it in connection with horn. The ivory was well-wiped with benzine before immersing in peroxide, probably because benzine removed a lot of surface oil.

Regards,
Neil

I need to be more diligent in bookmarking old texts I come across, but I seem to recall translucent amber colored horn was often made as a result of heating horn for a certain period of time and at a certain temp.

Don't quote me on that though....

Chris L

The following link isn't the one I was thinking of, but it's one I bookmarked a few years back and has some interesting things to say about the process of preparing horn sheets from raw horn:

HERE

I was almost ready to pull the trigger on some horn on Ebay and give it a try....

Chris - if the horn wasn't delaminated some time during the heating/pressing stages, a fibrous, opaque material is left near the core (the horn has had the tips cut off by now and been slit and opened out into a plate, so this inner surface is on one side of the plate and easily removed - a good thick horn could furnish a dozen leaves or plates after splitting). If enough pressure and heat are applied, the fibrous layer is squashed into a homogeneous layer and then becomes somewhat translucent.

The process usually fell into three phases: no pressing - horn used for the virtue of its natural shape, 1st pressing - horn plates from which to make combs, translucent plates for lamps and windows, etc, 2nd pressing - in which the horn is made plastic enough to be pressed into or against moulds and carvings.

Some of the translucency was no doubt due to the practice of using tallow to coat a "leaf" of horn to stop it from sticking to the hot metal plates used to press it, but in the making of the covers for "lanthorns" (lanterns) the most translucent and light coloured leaves were chosen to begin with.

Regards,
Neil

This is an old thread, but I have just come across this patent on Google Patents:

Patent US2667475 - Bleaching kebatinous materials - Google Patents

Considering the amount of inexpensive black buffalo horn on the market, it would be a fine and handy thing if it could be effectively bleached. Maybe this patent, for obvious reasons, is exaggerating the uncertainty of hydrogen peroxide bleaching. But what they propose is grinding it into a fine water slurry, in which form the difficulty of bleaching was overcome by soaking it in hot water.

As the patent holders were buttonmakers, I suppose it was then used for the unpatentable process of hot-compressing it into a solid again. I think this would be amply strong for buttons, but perhaps not resilient enough for razor scales, and any pattern or grain would be lost. The process is difficult and smelly, and if you are content with something you can't tell from a plastic, it might as well be a plastic.

But the hot water treatment sounds promising, as something that might possibly render at least the surface layer more amenable to bleaching, if it was done after shaping and all but the final and finest polish. I don't think it could ever make it look like really light natural horn, since the inside would be opaque, but it might still be worth doing. I don't know whether boiling would be better than the 130 Fahrenheit they mention.

I believe that for bleaching horn the ordinary peroxide for dabbing on cuts, at about 3 to 5%, is quite useless. You need much stronger, and up to about 35% is sold on eBay and deliverable. I have tried ordinary hypochlorite bleach, but it has no effect when diluted, and at neat strength actually eats away the surface without lightening it.

I have been doing some experiments in an attempt to make the horn look aged. I have tried several things, one of which is to soak the horn in oven cleaner in an attempt to pull the oils out, then soaking it in acetone. It has a once effect but it is temporary, as soon as the scales loose the chemical the color returns. I will soon go from oven cleaner to professional strength hair bleach. I am hoping that I get some effect. So far my results have been less than the desired effect.

I see horn bowls that say they have been "flamed" and I like the effect. Is this a reaction to a chemical or are they really "flamed". I have some horn I guess I could test it out on...but if someone all ready knows...

I believe it is primarily ultra-violet light that ages horn, and logically exposure to stronger UV light than sunlight would accelerate the process. I have no idea, though, of the relative strength of sunlight and the various lamps sold for sunbeds, insect zappers etc. I am pretty sure those for detecting fake banknotes would be too weak, but sunbeds certainly tan people faster than the sun.

There is a possibility that with any of them, you would find yourself replacing an expensive tube every month and waiting a hundred years for a result. But it is worth looking into. The removal of grease might still be worth doing. Oil certainly makes a difference to what sunlight does to your skin.