Sign in to follow this  
MikeC

What's a good copal varnish recipe?

Recommended Posts

I have some gum copal, not sure what kind or origin, that's all the container says. Thinking of trying to make some varnish with it. I found this recipe

Take copal in powder, 1 oz.; essential oil of lavender, 2 oz.; essence of turpentine, 6 oz.

Put the essential oil of lavender into a matrass of a proper size, placed on a sand-bath heated gently. Add to the oil while very warm, and at several times, the copal powder, and stir the mixture with a stick of white wood rounded at the end. When the copal has entirely disappeared, add at three different times the essence almost in a state of ebullition, and keep continually stirring the mixture.

You varnish experts... Joe? What do you think of that recipe. Are there other recipes that you would recommend?

Share this post


Link to post
Share on other sites

Kremer pigments lists 15 different types of copal If you succeed in making varnish from the material you have will you ever be able to make more of it?

I wouldn't bother making varnish from an unknown resin, the chances of success are limited and the reward for success is frustration.

The recipe seems sketchy. It assumes a melting point of 100c (water boiling point) which is very low-likely to result in a varnish that's too soft and delicate. Besides most copals have a higher melting point.

Oded

Share this post


Link to post
Share on other sites

I have almost a pound of it. I may as well try doing something with it. what the heck, just for fun.

In case no one noticed. I'm a code slinger by profession, sometimes fx trader, and an all around computer nerd. So I'm the guy who goes in the server room and says Hey! let's press this button and see what happens!

LOL

different varieties. hmm... is there any way to guestimate what kind it might be by it's melting point or hardness or specific gravity or something?

Share this post


Link to post
Share on other sites

You've been warned!

Most copals need to be 'run' (melted and cooked) before they will fuse with oil to make varnish.

First thing i would do is crush a bit and put it in alcohol. If it's soluble in alcohol you're done. If not then I would put it away and not think about it for a few years.

Oded

Share this post


Link to post
Share on other sites

I have almost a pound of it. I may as well try doing something with it. what the heck, just for fun.

In case no one noticed. I'm a code slinger by profession, sometimes fx trader, and an all around computer nerd. So I'm the guy who goes in the server room and says Hey! let's press this button and see what happens!

LOL

different varieties. hmm... is there any way to guestimate what kind it might be by it's melting point or hardness or specific gravity or something?

Try covering a bit of it with alcohol. If it softens, it's probably Manilla Copal.

Share this post


Link to post
Share on other sites

You've been warned!

Most copals need to be 'run' (melted and cooked) before they will fuse with oil to make varnish.

First thing i would do is crush a bit and put it in alcohol. If it's soluble in alcohol you're done. If not then I would put it away and not think about it for a few years.

Oded

Sounds like a plan, at least the alcohol part. Maybe I should use everclear so if the copal doesn't melt...

So manila copal is the only kind that will dissolve in alcohol? I'll try it and see.

Share this post


Link to post
Share on other sites

I have made spirit varnish for retouching by dissolving copal in alcohol and filtering it, then mixing it with dissolved, filtered sandarac and store-bought pre-mixed white shellac.

Share this post


Link to post
Share on other sites

This book has a lot of info on resins, may be able to help you identify the kind of copal you have.

Good luck and have fun, don't blow anything, except speakers.;)

http://openlibrary.o...s_and_varnishes

from the book:

In fusibility the hardest copals have the highest melting points. Zanzibar melts at 24O°-25o° C.: West African copals melt at 120°-180° C.; Sierra L,eone, 125°-137° C.; Manila and Kauri, H5°-i40° C.; Hymenea copal (fossil), i8o°-200° C., but the softer varieties melt below'115° C. The fusibility depends essentially on the age, the new varieties fusing at lower temperatures. In view of the complexity of composition no fixed temperature can be assigned to any variety. It must be pointed out that the resins first soften and then slowly liquefy and the running temperature is the point when suitable fluidity is attained which may or may not coincide with the melting point. For each gum there is a temperature below which it cannot be incorporated with linseed oil.

Morrell, R. S. (Robert Selby), 1867-1946; Waele, A. de (Armand), b. 1887. Rubber, resins, paints and varnishes (Kindle Locations 1727-1733). London, Baillière, Tindall and Cox.

Share this post


Link to post
Share on other sites

Very cool books but there is a danger of being completely distracted and spending the rest of your life chasing ephemera. Keep in mind that basically violin varnish was found to contain two ingredients, oil (linseed or walnut) and pine resin.

Varnish making and research should be regulated by the DEA as being highly addictive. You've been warned ! :blink:

Oded

Share this post


Link to post
Share on other sites

Hi Oded

with the copal I was thinking more of a ground than a varnish. The ground I've been experimenting with is mostly pine resin. It has some nice charactheristics but some other resin might be harder & more durable. Maybe a blend, one for looks and one for toughness.

I'm already adictied! :lol:

Share this post


Link to post
Share on other sites

So manila copal is the only kind that will dissolve in alcohol? I'll try it and see.

Since you've downloaded the book and pdfs, you probably know more than I do now. :-)

I don't believe Manilla Copal is the "only" one, but it is common, and goes into alcohol relatively easily.

It can also be melted and cooked into oil. I've made some rather nice workable oil varnishes (in combination with one or two other resins) with it.

Brad mentioned touchup varnish. I sometimes use a small amount (low ratio w/other resins) in alcohol based touchup varnish as well, but careful... it can be rather shiny. Used in larger ratios, and allowed to "settle out", it can make a very good base for fill varnish.

Share this post


Link to post
Share on other sites

I made some varnish recently using copal that i had had lying about for years, which Joe Robson said was probably Pontiak. I run it twice and left it cooking for quite a while after initially not heating it long enough.The colour was very nice and i cooked it directly afterwards with some slightly softer resin and oil. It turned out very nice ,good colour and it drys very well and fast,even without UV.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.