heat treating sealant questions

[ohiocountryboy]

In tbb 4 when he talks about heat treating he says he uses spruce gum and terpintine i cant find spruce gum  what are good substitutes?

[PatM]

Most conifers will have similar resin. 

[ohiocountryboy]

No clue how to harvest or even what it looks like .

[Joec123able]

I know spruce gum looks like pine resin and smells like it to

[PatM]

It's the stuff that oozes out when you cut off a branch. The resin oozes out and looks rather similar to honey. It dries out and may crystalize and appear sugary.
 Look at any conifer that has had branches pruned or broken off and you will see it.

[Pat B]

I used that process just last week on a persimmon bow I'm building. I used pine pitch dissolved in turpentine.

[JW_Halverson]

There was never any good explanation (to my mind) WHY Marc does this while he heat treats.

[ohiocountryboy]

what should i use then? he said in the beginning he  brushed water  on it but switched to the varnish

[JW_Halverson]

Plenty of people treat the belly's of their bows with fresh air as they heat treat 'em.

[zenart]

There was never any good explanation (to my mind) WHY Marc does this while he heat treats.

A guess:  Replenishing the wood to help avoid a brittle dry condition that heat produces.  Turpentine is a distillate from pine balsam. Adding the 'spruce' resin just makes it thicker. Could also use pure balsam extract but its very expensive.

My guess is he switched from water to solvent because it penetrates quicker and has a more 'relaxing' effect on the wood fibers… again, just a guess. Anyway, turps are -HIGHLY- flammable so watch it.

[PatM]

It very likely also has the effect of shoring up the cells the same way Osage or Yew Heartwood has improved compression abilities due to the resin content.
  There was a product called toxwood that was wood impregnated with phenolic resin or similar that was used as a belly material in the early days of synthetics.

[Pat B]

Marc told me it was to replenish the oils and resins that are forced out of the wood due to deep heat treating. It probably makes the wood less brittle. It sure soaks it up.

[Carson (CMB)]

I havent tried rosin/turp mixes while heat-treating, but I can say that I really like shellac for this purpose.  Fresh dewaxed flakes dissolved in den or pure ethanol alcohol.  It penetrates the wood and plasticizes under high heat.  Its affects really shine in the osage early wood or any ring-porous wood for that matter.  It fills the empty spaces and makes for a more homogenous material.  Sands smoother too.  If the early wood rings are thick, use a substrate like pumice, wood dust from sanding or earth pigments to bind with the shellac and fill the larger pores. 

[Marc St Louis]

My reasoning for doing this is that I figured that the high heat was forcing out air from the wood cells and instead of letting the air get sucked back in as the wood cooled I would give it something else to get drawn in.  It is surprising how deep the resin gets sucked into the wood.  I have used other things besides Spruce resin.  In fact I started out by using Tung oil but that was starting to get a bit expensive.  Spruce/Pine resin is free, for me at least.

[JonW]

I used Marc's method on a Hickory bow and I was very impressed. The bow does seem to be impervious to moisture unlike what you would expect from Hickory.