Where does the pitch go?

[Riles]

For those of you who have set the pitch in pine, where does it go? Does it evaporate or does some of it puddle up on the floor of your kiln?

[scsmith42]

I think that it crystalizes and stays in the wood...

[Den Socling]

The volatile components evaporate and the remainder solidifies at room temperature.

[Riles]

Just so long as it doesn't solidify on the kiln floor!

Do you notice any difference between dh and vacuum kilns with respect to setting the pitch?

[Tom]

We use that solidified pitch for glue.  When I find a big ball of it hanging on a tree, I break it off and put it in my tackle box.  If the rod tip comes off, just take a match, heat the resin and spred it on the top of the rod and then stick the tip back on.  In a few seconds, the resin will solidify and the rod will be as good as new. ;D

When I'm sawing SYP, I get a lot on the ground.  I've often wondered if I might be missing a market there.  :D

[Den Socling]

Many DH kilns can't set pitch very well. What you need is a temperature high enough that a hot, sunny day doesn't make the pitch bleed.

In a vacuum kiln, the low pressure pulls volatile compounds so the pitch is essentially set to a much higher temperature than the wood actually reached.

[Ianab]

The lighter components of the pitch evaporating is what makes a stack of drying pine smell so neat  ;)

[Den Socling]

The shop smells great when the vac pump starts, also.

[SwampDonkey]

What's in the pitch boys?  Deep breath now. ;D :D :D :D

[Den Socling]

Do you want all the organic compounds listed by molecular weight?  :D 

[SwampDonkey]

Well, we could compare notes, cause I might be missing something. ;D :D :D :D

let's see...

C₁₀H₁₆ turpentine

C₁₉H₂₉COOH resin acids

C₇₆H₅₂O₄₆ tannins

These books are dangerous. ;D  :D :D

[4woody]

SwampDonkey how long did it take to learn all that stuff that is way out of my leag

[Tom]

Didn't take me long.   I just call it .........money!  :D

[SwampDonkey]

4woody, I had a high school teacher that filled black board after black board....and she was still writing when the bell rang.  ;D :D :D :D I understood most if it them, but I've forgotten a whole bunch, if not most. That was extended somewhat in University. And I still forgot it since.  Ok, enough about what I don't know. : :D In University, I didn't study the molecular level of wood, just it's structure such as tracheids, perenchyma, resin canals, ray initials (wood rays), fusiform initials (cells), vessels/pores (spiral thickening, tylosis, scaloriform perforation plate) all that fun stuff. All that other stuff with molecular formulas were left to chemists, they're good at it. ;D :D

And like Tom, sniff sniff  .........the smell of money. :D ;D

[stumpy]

Is it true that the pitch sets to the hottest temp it reaches?  In other words, If I get pine up to 100 degrees and then install it on basement walls that never get over 70, I will not have sap bleed?

[jon12345]

 I think 160-180° is common, sometimes hotter. Otherwise anything that won't evaporate at 100° will still be liquid when it cools back down to room temp.

[scsmith42]

I typically set the pitch at 160F for 24 hours with my DH kiln.  The only time that I've had a problem is on very cold days.  If the outside temps stays below 30 degrees during this time sometimes I can't get over 150...  But then again my kiln is inside a metal shipping container, and if I insulated around the outside I probably wouldn't have a problem.

I have never noticed any residue inside the kiln.  Much more of a concern are the corrosive vapors from drying oak.

[Tom]

Stumpy,
you have the idea.  But, you can't just reach that temperature, you have to hold it there until the volatiles leave.

Kinda like bringing a pot of soup to a boil and letting it boil until just the vegetables and meat are left.

[Riles]

Is there any advantage to adding heat to a dh kiln, other than setting the pitch? I know the Nyle kilns come with electric heaters I assume are used to set pitch, but what if your kiln was set up in a building that already had radiant floor heating? It would make it easier for the heaters to get to 160 degrees but would it mess up the kiln schedule?

[Gary_C]

It depends on what wood you are drying. If it is a wood like oak that is difficult and slow drying, yes you could easily overdry. In pines or other softwoods, probably not, however you can overdry pine so it gets brittle.

The electric heaters in DH kilns are primarily used to bring the temperature up when you start the cycle. At that time there is no reason to run the dehumidifier as there is little moisture in the air so the heater kick starts the drying cycle and then when the moisture builds up, the heat from the compressor is all that is needed.

The temperature to set the pitch is above any temperature the wood will see when it is used. For all but structural components, that temp is usually 160 deg so if you use the wood for furniture, etc. the heat generated when you do the final sanding will not cause the sap to run.

[DR Buck]

The electric heaters in DH kilns are primarily used to bring the temperature up when you start the cycle. At that time there is no reason to run the dehumidifier as there is little moisture in the air so the heater kick starts the drying cycle and then when the moisture builds up, the heat from the compressor is all that is needed.

Gary's right if what my DH4000 (WM version of Nyle DH200)manuals says.  The heater only comes on until the inside tempeture of the kiln reaches 80° F, then shuts off.   All heat after that comes from the compressor.  I've had my kiln up to 155 once, not to set pitch, but to kill bugs.   I haven't run any pine through it yet.