Corrugata burl cracked?

[ReverendThom]

I made an Atrax fountain pen a few weeks ago out of corrugata burl. All was fine when I finished and put it on my shelf.

I just grabbed it for letting to sell and it appears to be cracked all over. Is this common? Did I do something wrong?

It came from a lot of blanks I bought off someone getting out of turning so I'm not familiar with these types of wood yet.

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[1080Wayne]

Can be a lot of potential causes . Blank not in moisture equilibrium to your environment if you got it from a more humid region , heat generation during drilling and/or sanding operations which dry it too much , internal stress relief within the blank from drilling the hole , are the first ones to my mind .

Pen looks good . Should be possible to disassemble and refinish with CA .

 

[jttheclockman]

Needs lots more info to be any help. Is this the pen in question that you are showing??? Where is cracking and is the wood cracking (where on the blank) or is the finish cracking (where on the blank)?? What type finish and did you do the finishing. If it is the finish cracking now you must explain your method of finishing. Did the wood come wrapped in wax ??? When working with unknown woods it is always best to use with precautions and take steps to prevent premature cracking and will get into this depending on your answers to some of the above questions. Without those answers you will get a ton of possibilities and boy do I hate that. Could be this or could be that or could be. We can narrow the possibilities down more so. Help us help you.

 

[PenPal]

This is not a characteristic of this particular burl which is normally quite stable. I cannot be even certain it is labelled correctly. Unsound timber is best avoided IMHO. Patching up rubbish gives rubbish.

Peter.

 

[ReverendThom]

Thanks all.

JT here are the answers to your questions:

Here's a close up on the cracks.

It's a shellawax finish. Pretty certain it's the wood - would shellawax crack at all, though?

Cracking is in various parts of the body.

It did come wrapped in a soft sticky wax.

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[leehljp]

Pictures show several immediate reasons to me:

1. possible green / wet wood (shrinks when dried which causes cracking)
2. cracks on the end indicate that there may have been some glue left inside the tubes and when put together - that forces the tube to expand cracking the wood.
3. It seems that maybe the drill hole for the wood was very tight.
4. "Stored on the shelf" - if the shelf was up high, or in an area for sunlight to hit if for an hour or more a day - THAT will cause it. high up storage - there can be as much as 20° F, differences between the ceiling and floor in heating. Green wood assembled at waist level and stored at head level can see enough temp difference to cause cracking. Same thing happens with sunlight or sitting in a hot closed car. Tremendous amount of contraction-expansion.

5. Shellawax is primarily wax, not a lasting finish.

Another thought: "It came wrapped in soft sticky wax" - possible that it was wrapped in the wax before it was cured/dried, and the wax will keep if from drying out for sure.

 

[PatrickR]

You probably will never know what caused it exactly but have a few things to watch out for in the future.
The wax coating is a biggie. Always consider wax covered wood to be green. It's done right after cutting to reduce checking etc. Once coated, even a small piece can take years to dry.
In the future scrape or cut the wax off, weigh the blank (store it in an area without climate control) and then weigh it again in a month or so, repeat until it no longer drops in weight. I wait until I see it going up and down in weight with the humidity.

 

[ReverendThom]

Thanks so much everybody. I really appreciate it!!!

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[jttheclockman]

Well Michael, thanks for answering a few questions. We can now eliminate any finishing problems so it narrows down to the wood itself. Being the wood was coated in parafin wax to start with tells you it is a wood that is prone to cracking and was either cut when wet and coated to help dry slowly or was coated to prevent it from taking on moisture when it was dry. We will never know that now. But it also tells you that this wood has to be treated differently than others. Not knowing weather the wood was wet we have to assume this and proceed from there.

A few ways to do this is to strip the wax off the best way you can, with scraper then some mineral spirits and weigh the blank. Now you will need a sensitive scale to weigh small blocks of wood like a pen blank. Let it sit a few weeks and again weigh to see if it is getting lighter. If so it tells you the wood was wet when sealed so you now have to let it continue to dry and continue weighing until the weight stops changinging. Now you need to keep in a dry cool area so it does not take on outside humidity. If the wood does not change on initial weigh-in then the wood was dry and just sealed to prevent it from taking on moisture. so you can work with it right away.

If you own a moisture meter you can use that also instead of scale.

What you have shown is surface cracks and this indicates the wood was wet and when you turned it you exposed it to air temps and it dried faster than wood can expand and contract thus the cracks. Adding heat from turning tools and also sandpaper did not help the cause. Heat is always an enemy in turning wood. In my opinion there is no way to correct this now and chalk it up to a learning experience or you can do some experimenting. If you are capable of doing a CA finish you can try to clean the blank with acetone to get rid of the finish that is on there and mix some sanding dust in some med CA and apply it to entire blank hoping it seals the cracks and covers them. Then use a skew or scrapper and turn round and shape again. I would avoid sandpaper in fear of the heat thing again. I then would do a few coats of thin CA and then a couple coats of med and sand and finish as normal. Can not guarentee the outcome.

Moral of this story, using woods that have wax on them are a sign of they need to be treated differently. Unknown woods can and probably will crack. Good luck.

 

[ReverendThom]

Well Michael, thanks for answering a few questions. We can now eliminate any finishing problems so it narrows down to the wood itself. Being the wood was coated in parafin wax to start with tells you it is a wood that is prone to cracking and was either cut when wet and coated to help dry slowly or was coated to prevent it from taking on moisture when it was dry. We will never know that now. But it also tells you that this wood has to be treated differently than others. Not knowing weather the wood was wet we have to assume this and proceed from there.

A few ways to do this is to strip the wax off the best way you can, with scraper then some mineral spirits and weigh the blank. Now you will need a sensitive scale to weigh small blocks of wood like a pen blank. Let it sit a few weeks and again weigh to see if it is getting lighter. If so it tells you the wood was wet when sealed so you now have to let it continue to dry and continue weighing until the weight stops changinging. Now you need to keep in a dry cool area so it does not take on outside humidity. If the wood does not change on initial weigh-in then the wood was dry and just sealed to prevent it from taking on moisture. so you can work with it right away.

If you own a moisture meter you can use that also instead of scale.

What you have shown is surface cracks and this indicates the wood was wet and when you turned it you exposed it to air temps and it dried faster than wood can expand and contract thus the cracks. Adding heat from turning tools and also sandpaper did not help the cause. Heat is always an enemy in turning wood. In my opinion there is no way to correct this now and chalk it up to a learning experience or you can do some experimenting. If you are capable of doing a CA finish you can try to clean the blank with acetone to get rid of the finish that is on there and mix some sanding dust in some med CA and apply it to entire blank hoping it seals the cracks and covers them. Then use a skew or scrapper and turn round and shape again. I would avoid sandpaper in fear of the heat thing again. I then would do a few coats of thin CA and then a couple coats of med and sand and finish as normal. Can not guarentee the outcome.

Moral of this story, using woods that have wax on them are a sign of they need to be treated differently. Unknown woods can and probably will crack. Good luck.

Thanks, JT! Very helpful advice and insight

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