Steaming beech for veneer production
Questions and answers on various technical aspects of steaming beech lumber, preparatory to producing veneer. Includes ideas for further reading.
Q.
Please advise me how to steam 31 and 55 mm European beech boards, edged and unedged. Should steam with or without stickers, and for how long a time? What will assure color uniformity?
We have steam available that is between 102-103 degrees Celsius.
Q.
Is it absolutely necessary to steam or heat beech veneer logs before peeling? We wish to peel logs without taking this step. What are the pitfalls if we do so?
A.
If you do not steam beech logs before veneering, then you will have an exceptionally rough surface that adjustments of the pressure bar (or nose bar) will not fix. You will also have quite a variation in thickness.
Gene Wengert, forum moderator
Q.
Could you please advise if it is possible to peel steamed beech logs
after 50/60 days from the date of steaming?
A.
I do not know. However, steaming is done immediately before peeling; the effects of steaming disappear when the log is cooled (except for color changes). Gene
Concerning the steaming of sawn beech lumber:
The steaming treatment must be done directly after sawing. Under no circumstances may the moisture content be below the fiber saturation point, approximately 36-35% for European beech, anywhere in the wood, or the color will be uneven.
The standard practice is to use saturated low-pressure steam at 95-100°C and heat up the lumber to approximately 95°C, and keep it there for 6-7 hours for 4/4 (25mm) and 12-14 h for 8/4 (50mm) lumber. To get a richer color, just increase the time of the treatment. The lumber must be on stickers to ensure an even color, and must be kiln dried or treated against mold directly after steaming or it will be attacked by mold in a day or two.
Note on the steaming of lumber. To get saturated steam, often the steam pipe (2" dia) has a multitude of 1/4 to 3/8" holes drilled in it (every 12 inches). Then the pipe is submerged in a water trough in the kiln. See "Drying Eastern Hardwood Lumber," USDA Ag Handbook #528, for pictures. Gene
Q.
So now we wish to steam veneer (peeling grade) logs. Please advise how best we can set up: What type of steaming system, at what max./min. temp should we steam, how many hours, etc.? Any other useful advice would also be appreciated.
A.
You need a paid consultant for information this specific. However, the U.S. Forest Products Lab had a book (by John Lutz, I believe) called Cutting and Drying Veneer (or similar title). Contact the Lab library at library@fs.fed.us
Gene
Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?
Have you reviewed the related Knowledge Base areas below?
KnowledgeBase: Primary Processing: Sawmilling
KnowledgeBase: Wood Engineering: General
KnowledgeBase: Wood Engineering: Wood Properties
KnowledgeBase: Knowledge Base
Would you like to add information to this article? ...
Click Here
If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to review our Forum Guidelines.
Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.
When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.
Return to beginning of article.
|
