WOOD SOME THINGS TO KNOW

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Wildman

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What you need to know about making a pen whether using domestic or exotic wood. Please refer to appropriate chapter of reference, "Wood Handbook," for more technical information.

Forest Products Laboratory - USDA Forest Service

Since no reference can completely answer why wood does what it does would like to quote Frank Lloyd Wright," We may only use wood with intelligence only if we understand it."

While reference material can tell you about wood characteristics of various species and provide scientific data. Most of the data is a based upon averages for a particular species. I will talk about ball park numbers a lot without mentioning any species.

See chapter 13 page 5, Figure 13–1. Recommended average moisture con¬tent for interior use of wood products in different areas of the United States. A better working guide is Table 13-2 Recommended moisture content values for various wood products at time of installation also on page 5.

Neither figure 31-1 nor table 13-2 say anything about pen or woodturning bowl or spindle blanks. Those charts do not mention anything about wood species but they do give you ball park moisture contents to shoot for before turning pens or other kit projects where need dry wood.

So how do you get a pen blank to those ball park MC numbers?

a. You can weigh or use a moisture meter when get new blanks.
b. If your blank comes completely sealed in wax scrap or burn off wax from sides of blank.
c. Weigh pen blanks when you get them with either kitchen or postage scale. When wood stops gaining or losing moisture & weight should be at EMC.
d. Inexpensive but reliable digital moisture meter.
e. Store your pen blanks so have plenty of air circulation and no extreme temperature swings.

Example: I buy a pen blank from a vendor in the Midwest, scrap the wax off sides of the blank and set it aside for a week or two. Using my moisture meter get a reading of 12% MC. Buyer from Arizona buys same blank from same place, does all the same things after a week or two gets a reading of 7%. The annual average relative humidity in my area is about 85% and his is only 38%. We are both probably at EMC.

Several charts online can tell you average annual relative humidity for your area. Closest city to me on charts consulted is Wilmington, or Raleigh NC.
Average Relative Humidity USA

To recap, with aid of references you can start to develop general plan for dealing with wood before you turn it.
 
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keithbyrd

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Thanks for the reference pointing and comments. This prompts a question that I have but have never asked. Using various techniques you can ensure your wood is at EMC for your area. You make a beautiful pen and ship from a high humidity environment to a low humidity environment or vise versa. What happens to the wood in the pen with these changing conditions?
 

SteveG

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Thanks for the reference pointing and comments. This prompts a question that I have but have never asked. Using various techniques you can ensure your wood is at EMC for your area. You make a beautiful pen and ship from a high humidity environment to a low humidity environment or vise versa. What happens to the wood in the pen with these changing conditions?
That situation can cause problems. My example: I sold a Bloodwood Zen to a person living in low humidity conditions. (This can be almost anywhere, since a home or office with heat or AC will commonly have low humidity conditions.) What exasperated my situation was that the wood was cross-cut, so I was dealing with worst case: long blank and cross grain wood movement. The wood was at equilib-MC for me in Hawaii, but dried further at the customer's location. Result: multiple cracks, cross barrel as the wood shrank as it dried.
My solution is to use only stabilized woods for cross grain styles, which eliminates most of the issues with wood movement.
 

Wildman

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Woodturners use parts of the tree average woodworkers avoid. As woodturners we have the option to turn wet or dry wood depending upon what we want to turn. All we need is a simple plan for the wood we harvest or buy.

When harvesting wood for turning your plan should vary some based upon where you live, annual relative humidity & temperature. Also amount and size logs collected. Procedure may vary further if just cut down a tree, or found some logs alongside a road. Consumer grade moisture meters useless on freshly cut down trees. Most meters not very accurate above fiber saturation point (FSP 25 to 30 %).

General procedure; cut logs longer than actually need regardless of diameter. Splitting longs really a judgment call based upon what you normally turn, diameter of log, and time. End seal your logs whether you split them or not. Yes, good idea to remove the pith on large diameter logs but not all sizes. Store logs out of the weather and off the ground.

Wood loses moisture content 12 times faster from the ends of a log than from sides. Wood dries from outside in, slowing down the drying process, will prevent end checks and splitting. I prefer paraffin wax to other end sealer because has an MEE of 95 and cheap. Anchor Seal & Green Wood Sealer (wax emulsions) are excellent end sealers too. Paint is better than clear finishes for end sealing

Listed table 16-3 on page 14 because while paraffin wax not a finish it is used by wood vendors to protect wood as it moves from one location to another.

Table 16-3. Moisture-excluding effectiveness of various finishes.
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_16.pdf

People buying turning blanks often get wood completely sealed in wax. Wood dipped in single coat of paraffin wax has highest protection against water vapor transfer caused by relative humidity. Since have no idea what MC of wood before sealing recommend scraping or burning wax off the sides of a blank so can reach EMC at your location. Have to monitor wood you store because no matter what you use to end seal not a set it and forget it proposition. As wood dries it shrinks and becomes harder & stronger, changes in temperatures and relative humidity will cause end sealants to fail eventually.

I store my end sealed wood in a woodshed and before turning will bring into my shop so can reach EMC. When find end seal failure will bring into the shop, and cut away any mold or end checking. May or may not end seal again. Won't go into mold growth now but nice to know if your area is prone to it.

Please see Figure 14-1 Climate index for decay hazard. On page 2 chapter 14 of the reference.
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_14.pdf

I like to rough turn bowl blanks while still wet. Turn to uniform thickness (bottoms always little thicker) and set aside to dry in back of my shop. Never reseal, might use grocery paper bag storage for couple weeks, never plastic. If breaking for lunch or overnight might use a plastic bag while bowl blank still on the lathe. Humidity level to high here and would encourage mold & stain growth storing wet wood in plastic bags for too long. Same is true using shavings in box or paper bag too long.

Just got into hollow forms and like to turn wet and shoot for ¼" even thickness. I don't seal after turning but wood is dry before applying finish.
 

Wildman

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Burls, only experience is with 10" diameter unknown species that I destroyed trying to turn it. Crotches have never found one big enough to bothered trying to turn.

Have been harvesting, drying, and turning reaction wood for years with few problems. Several years ago found some Mulberry Wood after a storm. Long story short, gave me fits trying to turn a bowl from wet wood, ended up with few small candy dishes. Stored improperly cooked the wood and ended up cutting away checks & splits to salvage pen & spindle blanks. See Mulberry pictures wood turning from yellow to brown.

Hardwood trees & reaction wood; found in base of trees & limbs with crooks, curves and bows. Reaction wood forms at top of bends or bows. Conifer trees & compression wood forms on the underside of bends, bows or curves. Looking at a tree & limbs easy to spot reaction/compression wood. Cutting at the base of a tree or limb easy to spot reaction/compression looking at growth rings. I could not say that about a pen or spindle blank with 100% accuracy.

Because of different wood grain under tension reaction wood dries a little different. On wood with normal grain wood shrinkage across the grain but not much along the grain. With reaction/compression wood shrinkage uneven and shrinks 10 to 20% along the grain.
You may find reaction/compression wood does not cut cleanly and wood has a fuzzy or wooly appearance, or does not take finish well.

Recently started turning Long Leaf pine, and for first time seen juvenile wood. Included a picture of juvenile wood at bottom of a vase. Also pith crack on one side and none on the other.
 

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SDB777

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I'm sort of lost on the statement of not being able to find 'crotches big enough to bother with'? North Carolina should have at least a few trees larger then 20"DBH with a major crotch....

Wood is more about the 'feel' then a bunch of '.pdf'(not saying the information you've linked too isn't fun to read-I've read thousands of pages of 'wood related science'). And I have found more information just running a chainsaw and then bringing it home ride the bandsaw mill....

About 35% of 'things' sold are wood items here, we air-dry everything here-no kiln. We are always concerned when the 'children' make a trip to a new home, but I've never heard any complaints about the turning of them.... I typically offer timber when it gets to 9-13% on my meter, and in Arkansas during the summer....that's pretty dry.





Scott (keep cutting) B
 

Wildman

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Spalted wood, absolute unpredictability and inconsistency of the wood structure, amount of spalting, and pattern. Each piece is completely different from the next even a few inches either way from the same tree. I have turned many items besides pens over the years and have had several pen turners wanting to trade exotic pen blanks for spalted pen or spindle blanks. Selling items turned from spalted wood kind of a mixed bag. A cigar store which wholesaled cigar pens too could not keep them, at shows they sold okay. My spalted wood hand mirrors out sold anything else had to offer.

Where I live any wood species laid on or near the ground will start spalting shortly. Getting to spalted wood before it becomes worthless matter of luck. A tree laying on the ground in the forest for more than a year worthless to me. Firewood stored on the bottom of the wood pile about 4" off the ground in my woodshed gets the party started.

Professor Sara C Robinson has written many papers & articles on spalting wood and takes you way beyond my experience check out the entire site.

Spalted wood beginners guide
Beginner's Guide | Northern Spalting

So far have discussed only abnormal wood with unusual grain. If stored properly and allowed to reach EMC will make your pen/woodturning successful.

I include this, "Grain Orientation by Todd Hoyer," link to demonstrate different affects you can achieve if stop and think about it.

http://ghwg.ca/techniques/Todd Hoyer - Grain Orientation.pdf

Pen & woodturners seem to stop at end and torn end grain. Well obviously there is more to it than that. Technically, the word grain refers to the orientation of wood-cell fibers. That's quite different from figure, which describes the distinctive pattern that frequently results from various grain orientations. To understand this, it may help to think of the word direction following the word grain. All grain types except straight grain can be a blessing or a curse. Because wood with anything other than straight grain may be sawn to produce sometimes exquisite figure, errant grain becomes a blessing. In structural applications, such as home construction, lumber (mostly softwood) with other than straight grain loses some strength. And hardwood boards without straight grain require extra care in machining to avoid tea rout and other reactions.
 

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Wildman

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Scot was asked about writing a tutorial for placement in the library. Writing a PDF file for the library pretty arduous task especially without input from folks around the country or world that is why started posting here. Much of what have been posting has been mentioned here more than a time or two over the years.

If notice while recommend the Wood Hand Book, not the only source linked. Those chapters, charts and figures cited from the hand book and linked should help folks put together a plan whether they buy or harvest their own wood for turning.

I get what you are saying and ask that you and other members contribute here anything have to offer.
 

oldtoolsniper

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I have had zero experience with the blanks that are part wood and part casting resin. I have had a lot of experience with wood and it's movement, and some of the frustrations it can cause.

If, I mean when the wood moves does it separate itself from the casting resin? I assume that the casting resin does not expand and contract at the same rate as the wood.

As I said I have no experience with theses types of blanks.


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jttheclockman

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I have had zero experience with the blanks that are part wood and part casting resin. I have had a lot of experience with wood and it's movement, and some of the frustrations it can cause.

If, I mean when the wood moves does it separate itself from the casting resin? I assume that the casting resin does not expand and contract at the same rate as the wood.

As I said I have no experience with theses types of blanks.


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When those blanks are being made the wood is stabilized so there is no wood movement.
 
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