Colophony shelf life

[Jim Bress]

I'm getting ready to make my first oil varnish using the Hargrave method.  I just started washing my linseed oil today.  Unfortunately Kremer dark brown colophony is back ordered.  I didn't realize that until after I ordered it.  Over the phone I was told 3 or 4 weeks, but I don't think they really know.  I just placed an order through Wood Finishing Enterprises for some of their FF (dark) colophony after verifying they had it in stock.  I can keep both orders or cancel my Kremer order.  The deciding factor is really a question of how long this stuff last on the shelf without cooking it before it begins to degrade for the purposes of making varnish or cooking for color?  Thoughts?  Experiences? 

Thanks,

Jim

[Bill Yacey]

I can't say with any certainty, but I would guess 500 years +.

[Thomas Coleman]

Purely intuition but I'd have to agree with Bill.

[Conor Russell]

One thought Jim. 

In my experience the dark grades are, in terms of varnish colour just marginally darker than the blonde grades. A few hours of cooking, and the pale stuff will have caught up. The dark rosin can give a slightly green tinge to the varnish. So, better to cook for that extra hour or two.

I'd suggest that you cancel Both, and get some pale stuff. 

[Michael.N.]

60305 is the stuff that I used. Kremer even state that it is suitable for violins. In the past I've used powdered rosin (not Kremer) and that was obviously light in colour too.

[Davide Sora]

If you keep it in lumps may last forever, but if it is powdery it is easily oxidized and it will cause problems with aging.

[Jim Bress]

4 hours ago, Conor Russell said:

One thought Jim. 

In my experience the dark grades are, in terms of varnish colour just marginally darker than the blonde grades. A few hours of cooking, and the pale stuff will have caught up. The dark rosin can give a slightly green tinge to the varnish. So, better to cook for that extra hour or two.

I'd suggest that you cancel Both, and get some pale stuff. 

Thanks Conor, I noticed a slight greenish hue in my test samples when viewed in the sun.  I had to balance the green by adding more red to my ground.  Good advise.  I'm going to cancel my order with Kremer and try to change my order with WFE if I can catch them before it ships.

-Jim

[Jim Bress]

2 hours ago, Michael.N. said:

60305 is the stuff that I used. Kremer even state that it is suitable for violins. In the past I've used powdered rosin (not Kremer) and that was obviously light in colour too.

Is that a Kremer number?  I wasn't able to find it.

[Jim Bress]

1 hour ago, Davide Sora said:

If you keep it in lumps may last forever, but if it is powdery it is easily oxidized and it will cause problems with aging.

Hi Davide, That's what I was worried about.  I think a store is a great place to keep extra materials, and it cuts down on clutter. 

-Jim

 

[Jim Bress]

8 hours ago, Bill Yacey said:

I can't say with any certainty, but I would guess 500 years +.

Would I have copal then? 

[Michael.N.]

29 minutes ago, Jim Bress said:

Is that a Kremer number?  I wasn't able to find it.

 

Yes. It's the stuff in a jar. Try putting that number in Kremers search box.

[Michael_Molnar]

I thought I told you at Thrift's Workshop that this stuff keeps forever. You could put it in a sealed jar which stops any oxidation. However, oxidation is good for color.

[Jim Bress]

10 minutes ago, Michael_Molnar said:

I thought I told you at Thrift's Workshop that this stuff keeps forever. You could put it in a sealed jar which stops any oxidation. However, oxidation is good for color.

Come on Mike.  Can you remember everything that went on in that 2 week whirlwind? 

-Jim

[Jim Bress]

Mike, Conor's post is what really changed my mind because of the green tinge that he associates with dark colophony.  I found this to be true in my own test samples, and I believe someone mentioned it in your bench thread conversation.

Edit: It was Don Leister referring to overcooked Diamond G rosin.  So dark rosin may be a factor or overcooking may be a factor.  I'll just have to learn from doing.

-Jim

[Michael_Molnar]

Or someone wasn't listening to me. 

I don't like the way FF rosin cooks in varnish. It doesn't work well to make rosinates either.

You should have the list of rosin suppliers and prices I pulled together during breakfast at the motel. Since you are new to this, go at first with the inexpensive Diamond G rosin. 

[Nick Allen]

Think of how ancient tree sap keeps for millions of years. You could even cast yourself in colophony and be preserved forever! 

Or is that ancient Amber stuff different from colophony in that colophony is a byproduct of the raw sap? Would that affect it's seemingly infinite shelf life?

[Michael_Molnar]

Amber is a horse of another color. 

[J.DiLisio]

Out of curiosity, does anyone know if the Kremer Dark Colophony is the same stuff as the Wood Finishing Enterprises FF grade?

 

[Michael.N.]

2 hours ago, Jim Bress said:

Mike, Conor's post is what really changed my mind because of the green tinge that he associates with dark colophony.  I found this to be true in my own test samples, and I believe someone mentioned it in your bench thread conversation.

Edit: It was Don Leister referring to overcooked Diamond G rosin.  So dark rosin may be a factor or overcooking may be a factor.  I'll just have to learn from doing.

-Jim

Over cooking/temperature too high can certainly produce a greenish colour. I've done it, yucky green brown. I still have the varnish. The only good thing is that it dries very fast. That's not much use when you can't use the stuff though.

[Jim Bress]

2 hours ago, Michael_Molnar said:

Or someone wasn't listening to me. 

I don't like the way FF rosin cooks in varnish. It doesn't work well to make rosinates either.

You should have the list of rosin suppliers and prices I pulled together during breakfast at the motel. Since you are new to this, go at first with the inexpensive Diamond G rosin. 

Pick your poison.  Didn't hear you, or failing memory.  If I did hear you I probably would have grilled you for information, like how long have you stored colophony and found it as good as when you got it.  I do still have your supplier list (Thanks!)  I didn't buy Diamond G initially because Joe said just buy the darkest stuff you can find.  See if I was paying you to work in your shop for 2 weeks I probably would have payed better attention.   

After finding out my original order from Kremer was back ordered I did a bunch of reading here on MN.  In one really long varnish thread a MN'r was having a really difficult time getting the Diamond G rosin to darken.   I know you like the Burgundy from WFE.  I decided against that because it was listed as a gum.  My interpretation was that the turps had not yet been distilled or cooked out of it to make rosin.  No big deal normally, but if you remember I am sensitive to turps so I thought it would be safer to get the pine rosin that specifies that the turps have been distilled out of it already.

"I don't like the way FF rosin cooks in varnish"  Well hell, I've had an order back ordered, placed an order for FF, then changed it to WW.  It's time to just "ready, shoot, aim".  I'll let you guys no  whether I fall on my face, or land on my feet.

Cheers,

Jim

[Jim Bress]

40 minutes ago, DoorMouse said:

Out of curiosity, does anyone know if the Kremer Dark Colophony is the same stuff as the Wood Finishing Enterprises FF grade?

 

Kremer's Dark Colophony is from European pines.  I wrote to Kremer's and they couldn't get more specific than that.  Wood Finishing Enterprises doesn't specify for the FF grade, but is likely the same as their other pine rosin which is made in the U.S. from Slash pine (Pinus Elliotii).

[Jim Bress]

47 minutes ago, Michael.N. said:

Over cooking/temperature too high can certainly produce a greenish colour. I've done it, yucky green brown. I still have the varnish. The only good thing is that it dries very fast. That's not much use when you can't use the stuff though.

Thanks I'll watch out for that.

-Jim

[Michael_Molnar]

1 hour ago, Jim Bress said:

Pick your poison.  Didn't hear you, or failing memory.  If I did hear you I probably would have grilled you for information, like how long have you stored colophony and found it as good as when you got it.  I do still have your supplier list (Thanks!)  I didn't buy Diamond G initially because Joe said just buy the darkest stuff you can find.  See if I was paying you to work in your shop for 2 weeks I probably would have payed better attention.   

After finding out my original order from Kremer was back ordered I did a bunch of reading here on MN.  In one really long varnish thread a MN'r was having a really difficult time getting the Diamond G rosin to darken.   I know you like the Burgundy from WFE.  I decided against that because it was listed as a gum.  My interpretation was that the turps had not yet been distilled or cooked out of it to make rosin.  No big deal normally, but if you remember I am sensitive to turps so I thought it would be safer to get the pine rosin that specifies that the turps have been distilled out of it already.

"I don't like the way FF rosin cooks in varnish"  Well hell, I've had an order back ordered, placed an order for FF, then changed it to WW.  It's time to just "ready, shoot, aim".  I'll let you guys no  whether I fall on my face, or land on my feet.

Cheers,

Jim

5

I remember Thrift saying to use the darkest rosin you can buy, but that was for HIS recipe. Mine is different. My tastes are different. You can use FF, but I won't.

You are sensitive to turps. I would be careful of the vapors from the pot for the first half hour of cooking. There are volatiles in all rosins especially the gum rosins.  Diamond G has a lot in my experience, but it evaporates quickly. Caveat emptor.

[Michael.N.]

I don't know what grade the Kremer stuff is. I don't think it is stated. I have bought some WW grade from another supplier but I've none of the kremer stuff left, so I can't directly compare. It probably doesn't matter, a varnish of some sorts will result. Next batch will be the Roger H. rosin straight into oil, the one he calls 'boring'. I don't need colour ( for a guitar) but I do need reasonably hard, so 60% 40% resin oil ratio might do it.

The last one I did was cooked at 200 C or under. It has some colour and rather nice it is too, if you like yellow/amber. 

[Uncle Bob]

10 hours ago, Jim Bress said:

Would I have copal then? 

Apart from having the secret to immortality, you would have extremely low and slow cooked colophony.