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Pitch for gravering.


Bartosz Ulatowski

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I have one question to those who has more experience with this product.

I have bought natural pitch for gravering. It is black with gentle smell of resin I think. It melt's very easily and after cooling it is very hard like plastic. But I have one problem. I put it on my copper plate which is rotative and witch I use for gravering. I put tsuba on it and it was great until I wanted to make some bigger dots and I strike my hammer with a little more force.

Then pitch broke like ice and it was all over my workshop. I was surprised because artificial pitch never behave like that. Of course I don't like this effect.

 

So please tell me what I have done wrong? Is it the copper plate? (it is 2mm copper plate glued into rotative round wooden board).May be I should use only wood? Or maybe I suppose to do something with the pitch before I use it?

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Hi Bartosz,

 

it sounds that your pitch is made of pine resin with some pigment (graphite or similar stuff). In some recipes it is stated to add a small amount of linseed oil , tallow or bee wax to the molten pitch. Just try to with a small heap of your pitch to test the response of it. But be very carefull while melting - molten pitch is extremly flammable. Test the brittleness with a hammer blow to check the desired result. This way you can create a range of pitches usable for chasing to repousse work. (To increase stickiness add a pint of turpentine)

 

regards

Karl :ph34r:

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Japanese Pitch has a number of fillers in it to get the right properties as Karl indicated. I have no idea what is in your product, but it maybe lacking one or more of the fillers.

That being said Japanese pitch is supposed to be hard and is somewhat brittle when it is not warmed up slightly. It does not work well in a cold room for example. You need to work it at a comfortable temperature. Preheating the entire assembly when setting your work will take away much of the internal stresses in the pitch and help keep the pitch intact through out the day.

Some things to keep in mind. Japanese pitch does not behave like commercial engraver pitch. It need a very rigid non flexible foundation. Preferably contained on the sides and bottom like in a rigid bowl. If your pitch went every where when it cracked I suspect it was exposed on the sides? My Tsuba often break loose of the Pitch through the course of a day when I get rough with it or use a power tools instead of Hammer and Tagane. It is a simple matter to wave the torch over them to relock them in. It does not happen if the pitch is properly prewarmed through out the mass.

It is a fine line between Hardness and toughness. You need it to be quite hard to prevent the work from distorting. If you make it too soft then you loose your support and the work suffers or sinks lopsided into the pitch. In the winter I keep the pitch bowl next to the heater when not in use and I set it on the heater in the morning to get the entire mass up to working temperature. My bowl has #25 pounds of lead to heat up and it holds the heat for a long time.

So keep in mind Temperature and rigidity. Is it warm enough? Are there any flexural stresses in your setup? Make some pitch as per Fords recipe and use that as a base line. Japanese pitch is quirky and you have to develop a relationship with it. It is worth it in my opinion so keep trying!

Regards,

Patrick

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Thank you both for advises.

A very small amount of bee wax(1/10) make my pitch little more flexible and I think this is what I want.

Yes temperature is important I have learned it when working with artificial. I have lamp near and it give enough warm. When I want strike harder I warm up it with a hear dryer and then pitch is not so brittle. But when I do gentle things it is strong enough.

It is new thing to me so I will be learning how to use it right but thanks to you I overcame my biggest problem.

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  • 2 weeks later...

One more question. What is the best solution to get metal out of pitch?

Because when you warm metal and try to pull a lot of pitch stick to a surface and there are a lot of work to remove it.

I put whole thing into fridge and wait when pitch freeze and then with one strong punch I take metal out with almost no pitch on it.

 

Is there any other ways?

 

(I will post soon photos of my last tsuba made by using pitch :) )

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Hi Bartosz,

 

there are two possible ways to remove your work from the pitch. When it is possible (no danger of wrapping or heat sensitive stones) you remove as much as you can mechanicaly and burn the remains.

The other way is to solve the pitch into acetone - do not smoke while working. This will remove your pitch quite fast and efficient. Simply put your piece into a pot with this solvent.

 

Hope this helps

 

Karl :)

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Guest ford hallam

Hi Bartosz, Karl,

 

you can also use turpentine to dissolve the pitch off your work, it may be a little cheaper and doesn't evaporate so quickly :) Naturally, take care not to inhale the fumes of any solvent so make sure you have decent ventilation. I know both of you are well aware of this, I just mention it for those who might not.

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