Full Chisel Blog

March 25, 2010

Cooking Blue Spruce Resin

Filed under: Finishing,Historical Material,Of Interest — Stephen Shepherd @ 8:51 am

Last fall I collected about 4 ounces of oozing sap from about a half a dozen Colorado Blue Spruce [Picea pungens] where I work seasonally.  Was largely a sticky job as some of the sap was fresh and some had a bit of a crust.  Well the other day I found my small crucibles and picked the tears and pieces of sap, removing as much foreign matter, e.g. bark and needles.  I then warmed the crucible up over my alcohol lamp and when it was molten I picked out the flotsam and allowed it to cool.

I then heated it up again, removed more debris and allowed it to cool.  I ended up heating it up three times because I didn’t have all of the particulates and then let it cool and the above photograph is how it looked after its last heating, cleaning and cooling cycle.  It started out as a sticky pile of sap and with each heating it became harder and harder.  I will heat it up one more time and pour it into cold water to make tears and drops that can be easily ground up into a fine powder.  This I will incorporate it in a batch of oil varnish.  It looks quite dark when it is deep but when it is a thin coat of varnish it will be a very light amber color.

During one of the heats I was holding both the alcohol lamp and a wire holder for the crucible in my hands when there was a flash from my alcohol lamp and I nearly dropped everything, I thought the resin had ignited but it was the alcohol lamp as I could feel little droplets of alcohol on the hand holding the lamp.  I have no idea what caused it to flash, perhaps it is not properly vented, any ideas?

Next time I cook some resin it will be in my new Tingry Varnish Furnace, picking it up this weekend.  Also getting an alembic and cucurbit and some pipkins.  This varnish making is fun but I am getting a few too many bottles of varnish, need to find more bottles or figure out what to do with all the stuff.  May have to start selling the varnish, the only problem is shipping.



  1. Dave,

    Would you please resubmit your post for some reason it was deleted.


    Comment by Stephen Shepherd — March 26, 2010 @ 6:10 am

  2. Found a copy in my email but with no name.

    If I may ask, what kind of alcohol lamp is it? Does it have a wick, or is it more of the style of one of those Swedish camping stoves?

    If it has a wick, then I have no idea whatsoever. If it is otherwise, alcohol, as a gas, is heavier than air and pools up. While handling it, this pool of gas within the lamp was disturbed, mixed with some fresh oxygen, resulting in a flash. The lamp will not do this normally, but it was the fact that you were holding and moving the lamp which caused the turbulence that mixed in the oxygen making it particularly sensitive to a flare up. Fortunately, these are almost always relatively small, although fun to watch. Alarming, yes, but relatively harmless. Just keep your eyelashes a safe distance away.


    Comment by Stephen Shepherd — March 26, 2010 @ 6:17 am

  3. Hi Stephen,

    This of interest to me. Fifteen years ago I reforested nine acres of land where we live in upstate New York and among the 8,000 or so trees are White and Red Pine, Blue and White Spruce, and Balsom Fir. In the pruning and thinning of these trees I certainly encounter plenty of pitch. I would like to know more about your collection technique, any books on the topic, photos, etc.



    Comment by Tico Vogt — March 27, 2010 @ 6:49 am

  4. Dave,

    I have a couple of alcohol torches [lamps] from Lee Valley, they have nice brass hardware and cap and with a wick. I have owned several over the years including a couple of nice old ones. I have never noticed this phenomenon before but it happens on both of these lamps. It is nothing dangerous, unless I were to drop a crucible of molten resin on myself, I am now quite careful and try to anticipate at least one or two flare ups during the cooking. I am careful not to heat the resin up enough to cause it to smoke as I am sure the fumes are flammable.


    I had a small cup and a small knife [actually a chip carving knife I carry while at work] and I would just wander amongst the spruce trees and scrap off larger drops and drips as they appeared. I never scored the trees to produce more sap but that can be done. You can also purchase a lot of different resins for varnish making but collecting the stuff on my own gives me a closer connection to the process. There haven’t been any recent books on the subject but I am currently working on my next book which will contain complete details for making varnish, paint and other nineteenth century finishing techniques.


    Comment by Stephen Shepherd — March 27, 2010 @ 8:07 am

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