Making natural varnishes

[WillS]

Do any of you guys know much about varnishes?

I'm working towards completing a set of historically accurate Mary Rose replica arrows, and one thing that I've been stuck on for ages is the final coating of verdigris compound over the fletch bindings. 

I've narrowed down most of the ingredients to the compound, but I'm having a nightmare trying to get it to set hard and durable - it always ends up too waxy and soft.

The basic ingredients are:

Verdigris powder (not important to the recipe but will be added once the mix is right)
Beeswax
Pine resin / colophony (Damar resin has been suggested for the same purpose but it's not historically correct for Europe in the Middle Ages)
Natural gum turpentine

I keep trying various mixtures suggested by all sorts of varnish making forums, from 50/50 mixtures of resin/turps to 30/70 etc and nothing seems to be working.  Adding the wax just makes it softer and more waxy, so I'm not sure why it's always included in the mixtures.

The end result needs to be fairly clear, easily brushable, but dry very hard and durable.

Any ideas would be most appreciated, as I'm running out of my own!

[Pat B]

I make a pitch varnish(not a true varnish) by dissolving hard, brittle pine pitch in denatured alcohol. I never use a recipe so amounts are hard to suggest. The hard, brittle varnish dries hard and clear(yellowish though) once the alcohol evaporates. I use this varnish on primitive arrows and sinew wraps.
 Years ago, in an old PA Magazine there was an article about making varnish using fruit tree sap. I just don't remember which issue.

[DC]

Do any of you guys know much about varnishes?

I'm working towards completing a set of historically accurate Mary Rose replica arrows, and one thing that I've been stuck on for ages is the final coating of verdigris compound over the fletch bindings. 

I've narrowed down most of the ingredients to the compound, but I'm having a nightmare trying to get it to set hard and durable - it always ends up too waxy and soft.

The basic ingredients are:

Verdigris powder (not important to the recipe but will be added once the mix is right)
Beeswax
Pine resin / colophony (Damar resin has been suggested for the same purpose but it's not historically correct for Europe in the Middle Ages)
Natural gum turpentine

I keep trying various mixtures suggested by all sorts of varnish making forums, from 50/50 mixtures of resin/turps to 30/70 etc and nothing seems to be working.  Adding the wax just makes it softer and more waxy, so I'm not sure why it's always included in the mixtures.

The end result needs to be fairly clear, easily brushable, but dry very hard and durable.

Any ideas would be most appreciated, as I'm running out of my own!

What are you using for resin? Like Pat says it has to be hard dry resin. If it's fresh it will never(well almost never) dry.

[WillS]

I'm using hard resin.  It's colophony, so it's like glass but really brittle.  It dissolves easily in natural turps, but is far too thin like that to be right.  It needs to end up quite thick and strong as its both fixing the bindings in place as well as adding the verdigris and waterproof layer all in one go.

[DC]

That's all I've got. Oh, I do use lacquer thinner instead of turps. Dries a bit faster.

[JoJoDapyro]

I'm using hard resin.  It's colophony, so it's like glass but really brittle.  It dissolves easily in natural turps, but is far too thin like that to be right.  It needs to end up quite thick and strong as its both fixing the bindings in place as well as adding the verdigris and waterproof layer all in one go.

HAve you tried to let the terps evaporate a bit first, leaving a thick product to apply, and with firm up after further evaporation?

[WillS]

No, I didn't know that worked!  Very interesting.  I'll give that a go tomorrow.

I found an old recipe using boiled linseed oil, turps and resin which I will try as well, but I suppose a large part of this is just finding the right quantities. 

[Pat B]

If I remember right the article in PA Magazine used an oil(possibly linseed oil) added to the mix. The bees wax would probably be the same as adding an oil.
Maybe use just enough turps to dissolve the pitch even if you have to keep adding the turps in small quantities.  Alcohol, lacquer thinner, acetone, etc. evaporate pretty quickly and the turps probably don't so having the correct mixture would be more critical for acceptable varnish.

[DC]

When I made it I put in just enough lacquer thinner to get it going. I didn't cover the pitch. As the pitch softens it sinks into the LT. You can always add more LT. Same would go for turps I would think. With LT if you add to much just leave the lid open until it looks like varnish. I guess the same goes for turps it will just take longer. I had to screen mine a couple of times to get rid of the bark and bugs.

[Marc St Louis]

The stuff I made many years ago was a pain to dry but I am thinking that the mix should be fairly thick and use heat to thin it for application, possibly a fair bit of heat.  Heating it would also drive some of the solvents out

[Jodocus]

I regularly make and use that type of varnish. Beeswax and resin, the rest is optional. The turpentine is the solvent naturally present in (and originally distilled from) the resin.

The mixture will stay soft and waxy for a while, but at some point it will dry hard. How long that is depends on temp and humidity and most of all the mixture and the qualiy of the resin. It is just not the kind of time we are used to from artificial varnishes or linseed oil with chemical siccatives. It's more like weeks, easily many of them. But it does dry hard eventually.

 

[Jodocus]

PS: the wax is in the mix to keep it from crackling.