Wood-mizer KD150 Series - Kiln Sample Boards; Uses for Sample Boards; Taking Samples

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To measure moisture content on a daily basis, it
is best to use sample boards. Moisture meters
are not accurate enough for most hardwood dry
kiln operations when the wood is above 30% MC
and there is a need to keep a close watch on the
drying rate. In Oak, for example, all checks and
honeycombing occur when the wood is drying from
green down to 40% MC, so that is when the drying
rate needs to be closely controlled.
• To estimate the MC of the load in the chamber, so
that kiln conditions can be regulated according to
drying schedules.
• To measure the drying rate, which allows control of
drying quality.
• To check on any degrade development.
• To check on nal MC and drying stresses.
• To develop a MC vs. time curve.
• To study variations in drying within the kiln.
• To monitor changes in MC after drying (during
storage and shipping) Note: It is a good idea to keep
sample boards with dried lumber so that they can be
used to track moisture content changes in storage.
Step 1: Select sample boards. Keep in mind that they
need to represent a “sample” of the lumber in the
kiln. Do not select junk boards, and select both the
slowest and the fastest drying boards of the load.
Generally, you want six sample boards.
Step 2: Cut 30” samples, at least 12” from the ends
of each of the sample boards. Avoid having knots,
splinters or bark in the sample.
Step 3: Number the samples you cut.
Step 4: Cut two 1” sections o each end of the
samples, and mark them with the number of the
board they came from.
Example: the two sections that came from sample
board 3 would be labeled 3A and 3B.
Step 5: Apply end coat the now 28” sample boards.
This assures that the sample board will dry as though
it were a larger piece of lumber.
End coatings are not usually required when lumber
is placed in the kiln directly after being sawn.
However when lumber is air dried prior to kiln
drying, end coating is often helpful in preventing
end checks U.C. Coatings is the major supplier of end
coatings. Contact them for further information:
U.C. Coatings
P.O. Box 1066
Bualo, NY 14215
Telephone: 716-833-9366
Fax: 716-833-0120
Step 6: Weigh the 28” sample boards. An accuracy
of .025 pounds or 1 gram is recommended. Record
these values.
Step 7: Put the 28” sample boards in the lumber
stacks in places where they can be reached and will
dry at the same rate as the lumber. Do not place the
sample boards where they will receive more air ow
than the rest of the lumber.
Step 8: Take the “green weight” by weighing all the 1”
sections, to 0.1 gram accuracy is suggested. Record
these values.
Step 9: Oven dry the 1” sections using one of the two
methods below.
Microwave with carousel tray: Put sections on a
paper towel on the tray. Use low power (to avoid
smoking) for 20 minutes. Weigh the section, and put
back in the oven for 1 minute. If the section has not
lost any weight, it is oven dry. If still losing water,
continue drying in 5 minute increments until a
Kiln Sample Boards
Uses for Sample Boards
Taking Samples
Wood-Mizer
KD150 12/22/17