Drying the pith

[olaf Vogel]

I tend to do a lot of end grain turning and try to leave the pith in - mostly because I love the look and patterns.
This makes drying a bit difficult. My success ratio has improved over time, by drying very slowly.

So of course, I looked for increasingly challenging pieces. Usually that means larger or at times quite decomposed.

I recently tried Minwax Wood stabilizer, on a blank that was rotted right through the centre. I poked out the really loose stuff by hand, pored on the stabilizer and managed to turn it normally. Surprise. Worked well, but expensive and STINKY!


(still covered in sealing wax)

This was the most extreme us I tried. I've also use the Minwax on the pith. Smaller ones I've hardened with Cyanoacrylate.

A recent web search turned up CPES: http://www.rotdoctor.com/products/cpes.html
Looks interesting.
Its intended as a marine product, but I thought it might work well for woodturning.

Has anyone tried this?
Olaf

 

[Charlie Knighton]

Olaf.....have not tried that

get you some mesquite

I have one more examplt....give me a minute

 

[Charlie Knighton]

here is the other, the blank was not 90 degrees but offset

the pith is in the sidewall

 

[Bill Boehme]

I feel like I need glasses, Charlie. 🙄

 

[JeffSmith]

Olaf - Having misspent years attempting to keep a moderately sized, not-quite antique but too old for it's own good, mostly mahogany vessel afloat - I'm very familiar with CPES and another product called Git-Rot. It's basically very thin, low viscosity epoxy that readily penetrates very dry wood in various stages of decay, fills interstitial spaces, and seals it from further penetration by water. Injected into wood that's barely held together due to dry rot, it can salvage that piece , turning it into a composite of the remaining wood fiber held together with hardened epoxy.
It works great for it's intended use - on wood that is very dry. don't know how it would fair in wood with various degrees of moisture content, though.
Also, you're essentailly creating a piece of plastic held together with wood fiber. Though I haven't tried it, turning qualities may be closer to turning brittle acrylic than seasoned wood.
If all that isn't too much of a downer, I'd give it a try, Just don't count on it to fill any cracks - it's far to thin for that.

 

[Charlie M]

This mesquite bowl is still in process, but I thought this would be a good example to show. Once the basic shape was turned, I used CA in the worst parts and then flooded with Miniwax wipe-on poly inside and out. Repeated the wipe-on poly as I finish turned and went through the sanding grits. It did not turn out as pretty or interesting to look at as I had hoped so it has set for several months. Just now getting back to finishing it.

Charlie

 

[Steve Worcester]

If it is dry, there are several options already discussed, wet, not really. Just turn thick with even walls and hope for the best

 

[olaf Vogel]

Olaf - Having misspent years attempting to keep a moderately sized, not-quite antique but too old for it's own good, mostly mahogany vessel afloat - I'm very familiar with CPES and another product called Git-Rot. It's basically very thin, low viscosity epoxy that readily penetrates very dry wood in various stages of decay, fills interstitial spaces, and seals it from further penetration by water. Injected into wood that's barely held together due to dry rot, it can salvage that piece , turning it into a composite of the remaining wood fiber held together with hardened epoxy.
It works great for it's intended use - on wood that is very dry. don't know how it would fair in wood with various degrees of moisture content, though.
Also, you're essentailly creating a piece of plastic held together with wood fiber. Though I haven't tried it, turning qualities may be closer to turning brittle acrylic than seasoned wood.
If all that isn't too much of a downer, I'd give it a try, Just don't count on it to fill any cracks - it's far to thin for that.

Thanks for the feedback. You were using it for its intended purpose at least. 🙂
One part of the description did say that it would displace water - thats what got me thinking.
Additionally, if the piece is rotted.

Overall, I was wondering if the product (and its marketing) had credibility or if it was just marketing.
Thanks - I will give it a try.

I have followed many of the other traditional recommendations.
My best solution so far is to coat the piece in Lee Valley Log End Sealer (aka Anchor Wax - I think). then dry it very slowly in a the cold storage room in the basement. Takes a long time, but results have been pretty consistent. Its when I rush it, that things go wrong. So my current strategy is to turn lots of pieces and then stack them up and wait - as I turner lots more...

Olaf

 

[JeffSmith]

One part of the description did say that it would displace water - thats what got me thinking.
Additionally, if the piece is rotted.

Olaf:
Since they market these products primarily for remediation of dry rot, I think that they may be referring to absorbed water more than the natural cellular water of green wood. But it's worth a try. I've used a fair amount of marine epoxy in both dry wood and some moderately wet woods that have deep, penetrating cracks and with mixed results. As long as the cure rate is slow enough, I get pretty good penetration. Usually takes at least two applications to get the cracks filled up.

 

[Bill Boehme]

.... One part of the description did say that it would displace water ....

Take the marketing stuff with a grain of salt. It's a lot like saying that water and oil don't mix. Expecting it to remove bound water, or even free water, is expecting too much in my opinion. My first thought is, "displace to where?" How does the water know where to go? The piece is being flooded from the exterior with the epoxy, so is it by some miraculous means supposed to pass through the epoxy and into the atmosphere? Doesn't make sense to me. If you want to get rid of something, there needs to be an easy path for it to leave -- otherwise water is just being trapped. My gut tells me that they would not mix well. There is always a tiny amount of moisture that is a consequence of the humidity of the local environment, called the equilibrium moisture content or EMC ... maybe that is what they are talking about.

 

[John Tisdale]

I do large hollow-forms which, more often than not, include a pith, or two, or three and more. The following is a few points for those who: rough turn - dry - second turn - finish
1) First Turn (rough turn) and leave at a thickness sufficient to allow for inevitable warp.
2) Boil for an hour or two - removes a bunch of stress/tension and makes the piece dry MUCH faster
3) Dry carefully - most fatal cracks occur between FSP (fiber saturation point or totally wet) and 20% - from 20% to 6% you can be aggressive
4) Apply epoxy as needed to dry piece - I use AeroMarine 300 which is a low viscosity - you can tint, mix with colloidal silica to thicken, and even shoot in a #22 syringe into small cracks
5) Put on the lathe and re-turn
6) Apply round-1 of finish and then use a good water-base putty for minor problems

While the above is simplistic, the basic principle is that, if properly dried, filled and finished, the pith is not a problem. But if you don't have the time/place to properly dry, best not to include.
John