Wooden Pens Cracking Over Time

[rkpgmp1]

Hi All,
I have noticed a larger number of my wooden pens (B&W Ebony, osage orange, etc.) cracking over the last several months. Does anyone have any ideas why, or advice to prevent? I can disassemble and re-turn, but I certainly don't want this happening with pens that I sell.
Thanks,Greg

 

[leehljp]

Greg,

Several things are involved with cracking and different circumstances with different woods also.

1. Unstabilized woods (on pens) can and will crack if they are green or have high moisture content when making them.

2. Many ebony woods (on pens) will crack with temperature swings.

3. Many woods (on pens) will crack with high humidity swings.

4. Most woods (on pens) will crack if left in a room (or automobile) with sunlight shining in and on the pens for a few hours each day or in a closed case that gets sunlight.

5. Most woods, even stabilized (on pens) will crack if left inside of vehicles that reach 110° - 120°+ over a day to a few days, even in the glove box.

6. Cross cut blanks will crack more readily than straight cuts if not stabilized. Cross cut blanks are more sensitive to movement issues in humidity and temperature changes than straight.

There are probably a few other reasons that I am missing. Others can chime in. It helps to know the situation - place of storage, temp changes, kind of finish, method of finish - used denatured alcohol, water base poly, CA, Wax only etc.

 

[Dehn0045]

I haven't been at this very long, but share the same concerns. Here are my thoughts on prevention:

1. Stabilize, eliminates moisture uptake and eliminates cracking risk. But stabilizing some woods is impractical or impossible. These woods require special care, like ebony, snakewood, etc.

2. Less heat while drilling. This is a common recommendation when working with Ebony, snakewood, or buffalo horn. Drill slow, clean and cool the bit with denatured alcohol.

3. Seal the drilled hole with thin CA and then carefully re-drill the excess. Also seal the end of the flush trimmed blank with CA. This will slow moisture swings.

4. Use a more flexible finish. I used BSI thin for a long time, but it seems to be brittle. Recently switched to Mercury flex based on reviews, not enough experience with it to comment on cracking. I also considered BSI gold, which also has good reviews. Medium CA will be more flexible than thin (in general).

5. Obviously proper care on the finished pen is necessary. Hank has this covered quite thoroughly in his post.

6. Start with wood that is close to equilibrium MC of the ambient condition of the pen. A pen that is made at EMC in South Florida will probably crack if it is sent to Arizona. There are threads about this specific concern. Store unstabilized blanks indoors, climate controlled area.

 

[1080Wayne]

Hank pretty much covered it . Assume they were made in the summer . Depending on where you live , winters can be much drier . Also possible that they were not fully dry to your ambient conditions when you made them . Dense woods can take a long time to come to equilibrium .

 

[monophoto]

Hank summarized it very well - wood expands or contracts with changes in humidity (mainly) and temperature. For most turnings, the expansion/contraction results in a distortion in the shape of the item - we call it artistic, and increase the price when we sell it. But if the ability to expand/contract is constrained, then movement is likely to result in a crack.

In the case of pens, the brass tube is a constraint - it's dimensions can't change, so if the only way that very thin layer of wood surrounding the tube can contract is if it first cracks.

I make wooden covers for jars and bottles, and I have several completed items on the night table next to our bed. A couple of months ago, I was lying in bed one morning listening to the NPR news when I heard a loud crack. I immediately knew what it was - a wooden cover on a metal jar lid had cracked. The wood was end grain and included the pith (I really do know better than than to do that!), and a crack had started at the pith and progressed out to the rim of the cover.

 

[PenPal]

Sorry I do not stabilise my timber pens but using timber I have had for some time helps me. Many yrs ago my wife showed me a quick test to see how dry timber is cut in blank form placing it on my wrist inside,if it feels too cold or moist it is noticeable.

Ok primitive but I have not lost a pen by cracking since.

When I was more active I put all my newly cut blanks in the roof space for a while layered in groups. I would choose a group and weigh it each week. When the weight became stable I brought it down to use in the future.

Thousands of blanks later it worked for me. Also I am ruthless when I find a weird,cracked etc blank it goes in the bin.

I do know getting all carried away ,purchase today and drill and fit brasses, turn later seems necessary to so many, you learn control much as bladder control,it has consequences.

I use great care and speed drilling blanks using hand control in the drill press. I used to do around two hundred at a time using a drill point drill,then I read the cost of a drill etc. When amortised over hundreds of drillings it is a meagre cost. I lose far more on glue drying up etc.

Sensible ,repeatable wins the day. Have fun I still do at 83 yrs.

Peter.

 

[PatrickR]

The long list of possibilities is the reason I stabilize all wood used in pens. I look at as insurance. I have stabilized ebonies and DIW. No, it does not absorb a lot of juice, but if you can draw air out of it you are adding CJ into it. If it does not crack during the drying, soaking and baking process the chances of it cracking later are far less.

 

[dogcatcher]

I don't stabilize any of my wood that is for pens. I drill the blanks and let them sit for a day or 2. That allows the wood fibers to "relax" from the lack of the wood that was drilled out and any heat related issues from drilling. Pool cue builders do like wise whne turning blanks, after each pass the allow the blank to "acclimate to the difference after removing wood.

 

[MRDucks2]

There are some woods that will simply crack. They are that hard and will see changes. All wood moves. With Snakewood, you may not see the cracks. With Curupay the cracks are easier to see, but will still happen. When and how bad depends on the kit and the cut.


Sent from my iPhone using Penturners.org mobile app

 

[Woodchipper]

dogcatcher, that is a good idea. So far, I haven't had any problems with the wood but why take a chance. Drill 24 hours ahead and then build the pen. Thanks.