Jump to content


Repairing split pieces


16 replies to this topic

#1 Buels Gore Wood Carving

    Newbie

  • Members
  • Pip
  • 6 posts
  • Location:Buels Gore, Vermont

Posted 02 March 2009 - 03:21 PM

I get all of my wood wet from the local forest, so it may crack upon drying, especially after I have taken off a good deal of material. Also, I have cracked a ffew pieces at the end of the carving process. Although I have become fairly good at repair, I feel some guilt as I put on the last coat of oil -- particularly if I have managed to make the flaw almost disappear. Can anyone comment on the morality of showing a complete wood piece that has a hidden flaw?
John Clarke

#2 Mike Ruslander

    Advanced Member

  • Members
  • PipPipPip
  • 404 posts
  • Location:Richmond, VA

Posted 02 March 2009 - 07:31 PM

Happens all the time.
One of the hazards of working with wood.
If you can make it disappear it's good (as long as the piece itself is structurally sound). I'll bet everyone here has done it. Wood glue and sawdust from the piece is my method. Superglue or epoxy and sawdust works as well.

#3 Buels Gore Wood Carving

    Newbie

  • Members
  • Pip
  • 6 posts
  • Location:Buels Gore, Vermont

Posted 03 March 2009 - 01:40 PM

View PostMike Ruslander, on Mar 2 2009, 02:31 PM, said:

Happens all the time.
One of the hazards of working with wood.
If you can make it disappear it's good (as long as the piece itself is structurally sound). I'll bet everyone here has done it. Wood glue and sawdust from the piece is my method. Superglue or epoxy and sawdust works as well.

Thanks, Mike. I feel absolved of my crimes. I will pull my Gorilla Glue out of hiding and sweep up another can of saw dust. One of the things I discovered about glue and sawdust -- or maybe others do it too -- is that hammering sawdust into a crack filed with glue seems better than just pressing it in. I borrowed that idea from nineteenth century sailors who have to beach their ships once in a while to hammer tar-covered ropes between the planks.

#4 Leon

    Advanced Member

  • Members
  • PipPipPip
  • 169 posts
  • Location:The Netherlands

Posted 03 March 2009 - 06:11 PM

Mike Ruslander said:

... I'll bet everyone here has done it. ...
Sorry Mike, you lost.
Never have, never will. Just don't like the idea.

(And I bet I'm not the only one.)

#5 Phil White

    Advanced Member

  • Members
  • PipPipPip
  • 450 posts

Posted 04 March 2009 - 12:52 AM

Hi John,

I think it depends on the size of the work in question. With larger sculptures, it is fairly common, and generally accepted, to infill cracks with small wedges of wood, usually the same wood that you are working with, being careful to match the grain and direction. The pieces are carved down with the surrounding wood and finished to match. I have seen this in older work as well.

However, the smaller the piece, the more obvious this type of repair becomes, and the less accepted it is.

Both Mike and Leon are correct.

Phil
Follow my work on Facebook

#6 Guest_Clive_*

  • Guests

Posted 04 March 2009 - 12:43 PM

If you're using wet wood surely you are readily accepting that cracks and splits are inevitable and therefore should form part of the character of the objects your making with that wood. I don't think its really a question of morality.. but really one of truth to that material. Is the wood you are using really suitable for what you want to do with it?

#7 Jim Kelso

    Advanced Member

  • Members
  • PipPipPip
  • 1,423 posts
  • Location:Vermont

Posted 04 March 2009 - 02:19 PM

I think it depends on context, as most others have suggested. Wood is a very lively material in the way that it responds to atmosphere and light. Cracks can be a deal-breaker or not. They can actually be celebrated. There are pieces by the lacquer genius Zeshin that are lacquer imitations of wood with simulated "repairs" of fake cracks, using little inlaid dovetails, or lacquer nails.

Sometimes you see cracks that are wired together.
Our three most valuable tools: our thumbs, our imaginations, and our good-will.

My Webpage

#8 Janel

    Administrator

  • Admin
  • PipPipPip
  • 3,638 posts
  • Location:Minnesota, USA

Posted 04 March 2009 - 03:33 PM

I am unable to find the support photos on the internet for what I have seen in books for woodturners who process wood for future turning.

The diagrams show the wood in cross section, with the pith (original trunk of seedling/sapling), heartwood and sapwood each of differing densities and moisture. The log section if left alone will split to relieve the tension from the uneven rate of drying. (I apologize for not getting it all quite right with the vernacular) The different areas of the log lose moisture at varying rates. Moisture is lost from the open ends of the logs, and from the outer areas sooner than the inner areas. As the moisture leaves the cells of the wood structure collapse or shrink, causing the cracks to form.

Processing wood for turning requires the elimination of the pith area from most woods. The pith, if left intact, will cause the wood to split. Large logs are divided around the pith into the size and orientation for future turning. The end grain is coated with a water-based emulsion of wax, which seals the ends to prevent rapid loss of water. I don't know how larger pieces of wood are handled for drying for future work, but I have learned that logs are cut into thick planks and then into hunks that will be used in the future as dry wood. These are dipped or coated on the ends and a ways up the sides with wax, placed on racks for the air to flow gently through the stored wood. Each layer of wood stored for drying is separated by dry wood "stickers" 3/4-1" thick, and each piece is placed in alternating positions over the layer below, so that the air is diverted around each piece rather than rising up in a straight shot. I do not know the rule of thumb for the various sorts of wood and the thicknesses for the period of drying to be completed. I may have heard an year per inch of thickness, but I won't take that as a fact. Books from woodworking sources are a great resource for such information.

At the wood worker's stores, one finds chunks of wood entirely coated with wax, and as described to me, these are not yet dried pieces, or perhaps they are very slowly drying. I have not been around enough turners to know why this is done and how it holds the wood for use, and if it is actually a preferred way to do the processing. Lots to learn yet!

Turners often use green wood immediately after cutting the wood, some will retain the pith. One key that I do know is that to dry with out cracking the vessel needs to be of an even thickness all around and on the bottom. Drying then is moderated after the piece is completed, and after drying is complete, the surface is then addressed by carving, sanding or finish applications.

I don't know it all yet. The key is that a log left intact will split. A carved wet log will crack most likely.

As Jim describes above, by anticipating the end result, the cracks may be an intentional addition, left to the idiosyncrasies of the wood. Knowing your materials and how they react to use or abuse, the environment while working, and the environment after it becomes someone else's all have a role in the longevity and success of a piece. That is a lot to learn and to experience.

John, I am curious about what you are carving and what your intentions are with your carvings. Do you want them to crack? Do you use the entire log because of the size? Do you keep some of the bark integrated in the design? Do you use green wood because of availability at the time you want to carve something? Might you try processing some wood for future use when you are cutting the green wood for immediate use? Sorry for so many questions, but if we were visiting over coffee, I would ask these of you.

Kindest regards,

Janel
Teachers open doors, you enter by yourself. Chinese proverb
What you can do, or dream you can, begin it; Boldness has genius, power and magic in it. ~ Goethe ~


Janel Jacobson's web site

#9 Dick Bonham

    Advanced Member

  • Members
  • PipPipPip
  • 552 posts

Posted 04 March 2009 - 03:39 PM

I have seen cracked Japanese pipe cases repaired using gold, silver or copper staples. Sometimes butterflies are employed. I have a pipe case that was eaten by worms and "repaired" by shakudo bugs being placed in the channels. In all cases the repairs were obvious.
Dick www.erbonham.com

#10 Buels Gore Wood Carving

    Newbie

  • Members
  • Pip
  • 6 posts
  • Location:Buels Gore, Vermont

Posted 04 March 2009 - 04:01 PM

View PostJanel, on Mar 4 2009, 10:33 AM, said:

I am unable to find the support photos on the internet for what I have seen in books for woodturners who process wood for future turning.

The diagrams show the wood in cross section, with the pith (original trunk of seedling/sapling), heartwood and sapwood each of differing densities and moisture. The log section if left alone will split to relieve the tension from the uneven rate of drying. (I apologize for not getting it all quite right with the vernacular) The different areas of the log lose moisture at varying rates. Moisture is lost from the open ends of the logs, and from the outer areas sooner than the inner areas. As the moisture leaves the cells of the wood structure collapse or shrink, causing the cracks to form.

Processing wood for turning requires the elimination of the pith area from most woods. The pith, if left intact, will cause the wood to split. Large logs are divided around the pith into the size and orientation for future turning. The end grain is coated with a water-based emulsion of wax, which seals the ends to prevent rapid loss of water. I don't know how larger pieces of wood are handled for drying for future work, but I have learned that logs are cut into thick planks and then into hunks that will be used in the future as dry wood. These are dipped or coated on the ends and a ways up the sides with wax, placed on racks for the air to flow gently through the stored wood. Each layer of wood stored for drying is separated by dry wood "stickers" 3/4-1" thick, and each piece is placed in alternating positions over the layer below, so that the air is diverted around each piece rather than rising up in a straight shot. I do not know the rule of thumb for the various sorts of wood and the thicknesses for the period of drying to be completed. I may have heard an year per inch of thickness, but I won't take that as a fact. Books from woodworking sources are a great resource for such information.

Turners often use green wood immediately after cutting the wood, some will retain the pith. One key that I do know is that to dry with out cracking the vessel needs to be of an even thickness all around and on the bottom. Drying then is moderated after the piece is completed, and after drying is complete, the surface is then addressed by carving, sanding or finish applications.

I don't know it all yet. The key is that a log left intact will split. A carved wet log will crack most likely.

As Jim describes above, by anticipating the end result, the cracks may be an intentional addition, left to the idiosyncrasies of the wood. Knowing your materials and how they react to use or abuse, the environment while working, and the environment after it becomes someone else's all have a role in the longevity and success of a piece. That is a lot to learn and to experience.

John, I am curious about what you are carving and what your intentions are with your carvings. Do you want them to crack? Do you use the entire log because of the size? Do you keep some of the bark integrated in the design? Do you use green wood because of availability at the time you want to carve something? Might you try processing some wood for future use when you are cutting the green wood for immediate use? Sorry for so many questions, but if we were visiting over coffee, I would ask these of you.

Kindest regards,

Janel

Janel,

The coffee sounds good. And so does the guidance. I really would prefer not facing a crack, but as you, Phil, Mike and others have pointed out, the cracks may not be a huge problem. I look for burls in the woods, hard maple, cherry and yellow birch, but also fall for strange contortions in any tree that has a human look. The burls may be as large as 4' in diameter, but usually are about 14". Burls do not seem to split, themselves. They also seem to dry fairly quickly. But, the trunk on either side of the burl will split. Anyway I pile them for a year, with their butt ends painted, then hang them in the shed for a year or two. Typically, the bark has fallen off by then and the wood may have begun to crack, or not. With the chainsaw, I try to find human forms. Then, I may carve a log to less than 1" in diameter, for legs and arms and such. At that point, I am looking at pith and heartwood, maybe with sapwood for color. A piece may hold up fine during carving in the shed, but split all the way when I take it in the house. (Wood heat -- lethal) Maybe the outer layers are drier than the inner core, which splits when air quickly draws out moisture. Someone in another area recommended soaking a piece in oil at intervals. Maybe, as you suggested, I should let the cracks form, then use them in the design -- if they show quickly enough. ?
Thanks for the careful thought.

John

#11 Mike Ruslander

    Advanced Member

  • Members
  • PipPipPip
  • 404 posts
  • Location:Richmond, VA

Posted 04 March 2009 - 08:41 PM

Per David Boye. Respected author of the book: "Step-by-Step Knifemaking".

Attached Images

  • Attached Image: David_Boye_Quote.jpg


#12 Phil White

    Advanced Member

  • Members
  • PipPipPip
  • 450 posts

Posted 04 March 2009 - 09:50 PM

John,

Most of the work that I do is relatively small. My personal approach is to rip the log in two pieces, just off center. The small piece is set aside to dry as is, and the heart wood is cut out of the thick piece with an adze. I have about 18 logs that I have prepared in this manner, several of which are around 18" wide, with only minimal checking on the ends, some after 12 years.

If you are working with larger pieces of semi-dry wood you may want to consider keeping your work covered in plastic while working on it. This is a technique used commonly by some Northwest coast Native carvers, who often prefer to work with semi-wet wood. I knew a carver who took the wood that he needed directly from large old-growth cedar stumps, then kept all of his blocks in garbage bags until he was ready to use them. This kept the wood from drying too quickly, and gave him time to hollow the work out from the back to remove internal stresses that cause cracking.

Another carver that I knew, who works with very large pieces often takes a similar appoach. He roughs out the form first, then makes a pre-emptive cut, for example in the back of the head, so that the stress will be relieved in a spot of his choosing. He then allows it to dry and infills the cut with the same wood.

Phil
Follow my work on Facebook

#13 paul

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 15 May 2010 - 02:49 PM

View PostBuels Gore Wood Carving, on Mar 2 2009, 05:21 PM, said:

I get all of my wood wet from the local forest, so it may crack upon drying, especially after I have taken off a good deal of material. Also, I have cracked a ffew pieces at the end of the carving process. Although I have become fairly good at repair, I feel some guilt as I put on the last coat of oil -- particularly if I have managed to make the flaw almost disappear. Can anyone comment on the morality of showing a complete wood piece that has a hidden flaw?
John Clarke
Hi John, my idea on this matter: don't feel guilty about repairing cracks in wooden sculptures/carvings :unsure:! It happens to every wood carver, even the most experienced ones. It's the wood that is a living and absorbing material, a material that shrinks a little while drying. Once I met some African wood sculptors in Tenerife-Spain, one of these guys showed me how they fix every little crack in African 'black ebony' sculptures like they produced for selling in Europe, they use black shoe polish to fill up the cracks and than high-polished the whole sculpture so nobody could see. He explained to me that it's better for selling, because his experience was that with any visible crack, a possible buyer could change his mind seeing it in the otherwise so beautiful sculpture! Kind regards, Paul

#14 Dave London

    Member

  • Members
  • PipPip
  • 29 posts

Posted 20 May 2010 - 11:46 PM

View Postpaul, on May 15 2010, 02:49 PM, said:

Hi John, my idea on this matter: don't feel guilty about repairing cracks in wooden sculptures/carvings :D! It happens to every wood carver, even the most experienced ones. It's the wood that is a living and absorbing material, a material that shrinks a little while drying. Once I met some African wood sculptors in Tenerife-Spain, one of these guys showed me how they fix every little crack in African 'black ebony' sculptures like they produced for selling in Europe, they use black shoe polish to fill up the cracks and than high-polished the whole sculpture so nobody could see. He explained to me that it's better for selling, because his experience was that with any visible crack, a possible buyer could change his mind seeing it in the otherwise so beautiful sculpture! Kind regards, Paul


Well I read a while back about some forest products outfit or govt agency don't remember which( happening more lately :unsure: ) Anyhow the wet fresh cut wood was being soaked in propeline glycol(sp)and this prevented checks and cracks

#15 cneber

    Member

  • Members
  • PipPip
  • 18 posts

Posted 22 May 2010 - 05:00 PM

View PostDave London, on May 20 2010, 04:46 PM, said:

Well I read a while back about some forest products outfit or govt agency don't remember which( happening more lately :unsure: ) Anyhow the wet fresh cut wood was being soaked in propeline glycol(sp)and this prevented checks and cracks


I would NOT use PEG (Polyethylene Glycol) because you cannot apply any type of finish that will not crack or flake off later.

#16 cneber

    Member

  • Members
  • PipPip
  • 18 posts

Posted 22 May 2010 - 05:23 PM

View PostBuels Gore Wood Carving, on Mar 2 2009, 08:21 AM, said:

I get all of my wood wet from the local forest, so it may crack upon drying, especially after I have taken off a good deal of material. Also, I have cracked a few pieces at the end of the carving process. Although I have become fairly good at repair, I feel some guilt as I put on the last coat of oil -- particularly if I have managed to make the flaw almost disappear. Can anyone comment on the morality of showing a complete wood piece that has a hidden flaw?
John Clarke

first, understand why green wood cracks. cracking occurs when there is an unequal release of free-water and cellular water within the mass of wood. Therefore, when the outside layers of wood loose more quickly than the interior, cracking occurs.

when wood is allowed to dry in a controlled environment, where the relative humidity is lowered slowly so that the rate of water loss between the interior and exterior is balanced, cracking is substantially reduced.

so, how do you produce this controlled environment? the timber industry uses kilns to slowly pull water from the wood, apply controlled heat to get the free-water and cellular water released. we can use the microwave to produce the same effect, but goggle this so you fully understand the method, and i would recommend using a dedicated microwave for this operation. additionally, you can build a simple vacuum chamber to dry -- again, goggle for details.

also, you can wax the end-grain of the wood and let the wood stabilize and air-dry. by measuring and charting the weight, you can determine when it has reached stabilization (~8-10%). by blocking the end-grain with wax AND storing on end-grain, most of the splitting and cracking can be prevented while drying.

i prefer waxing end-grain and air drying -- the wood is much nicer to work with than any of the 'cooking' methods. furthermore, after the wood has reached stabilization, any cracking can be cut off and there is no further cracking problems. the down-side is that you have to have the storage space for your collection.

#17 Ed Twilbeck

    Advanced Member

  • Members
  • PipPipPip
  • 308 posts
  • Location:Ocean Springs Ms

Posted 22 May 2010 - 07:18 PM

John after seeing your site and seeing what woods you work with I would not worry about repairing any cracks, splits or flaws in the wood. Your work is outstanding. Any one who works with burls would have to expect to have some repairs. Keep doing what your are doing.
Ed T.
Firewood Studio
Ed Twilbeck



1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users