December Newsletter 2015 Seasonal Changes in Wood Moisture


December 2015,

Issue No. 16


*Common Moisture Problems in Woood

* How Seasanol Changes in Humidity Affects Wood

Interesting Websites

How to Prevent Wood Floor Gaps in Winter

(see more)

Understanding, Preventing, Detecting and Correcting Moisture in Concrete Floors

(read more)

Keep in Touch:

PHONE: (800) 227-2105

            (503) 257-8957

FAX:      (503) 256-3844



Upcoming Trade Shows

Surfaces Trade Show in Las Vegas January 20th-22

Come visit our booth #4257

Click here for more information

World of Concrete Show in Las Vegas February 2-5 Come Visit our booth #S11655

Click here for more information

Common Moisture Problems in Wood

Wood is an ideal raw material: long lasting, sturdy, easy to shape, join together or glue and is continuously renewed.  Above all, wood is beautiful.  Everybody likes its durability, texture, looks, touch, color and unique design.

Wood is used in many different applications – from structural building components to hardwood flooring, from furniture to toys for kids, from cabinets to musical instruments.

The challenge of woodworking starts with choosing the right wood.  If the wood is not right for the application, the best tools and excellence in workmanship cannot guarantee a high quality product.  Wood species, grade and moisture content determine quality and usefulness of wood.

Common Moisture Problems

A chair with loose joints or a cabinet door that will not close.  A  butcher-block table with a big crack down the middle or a veneered surface that shows surface checks. Edge banding applications where the glue line fails.  A jewelry box with crooked joints and bent out of shape, cupped floors, foggy finishes, etc.

During air and kiln drying moisture defects such as case hardening, honeycombing, split ends or surface checks can occur. If wood is not properly stress-relieved, internal stress within the board can be suddenly released when a board is cut.

Moisture defects are irreversible. Immense stress within the wood permanently deforms or destroys the structure of the wood (cracking, checking, warping, honeycombing).    

Shrinkage between 18% and 6% in Red Oak.

At the beginning of the test both pieces ( 1 1/4” x 4”) had the same size and the same moisture content of 18%. The upper piece dried down to 6%, whereas the lower piece was kept at the 18% moisture level.

Why Moisture Problems Occur

Wood is not a homogeneous material, but structured by year rings, which form a series of more or less concentric cylinders. These cylinders consist of irregular tubes that transport nutrients and support the tree.Interaction with

Air:  When wood absorbs or looses moisture below the Fiber Saturation Point (28%-35%), the tubes expand or contract, causing wood to swell or shrink.  To the woodworkers dismay, shrinking and swelling is often accompanied by warping. Shrinking does not occur lengthwise along the tubes.

Changes in the wood moisture content occur until an equilibrium with the surrounding air has been reached.  At that point the equilibrium moisture content (EMC) of air is the same as the wood moisture content (MC).If wood pieces with different moisture contents were placed for a long time in a constant climate of 700F and 35% relative humidity, all wood would end up with a moisture content of 7% independent of the wood species or the initial moisture content.

Since 700F and 35% – 45% relative humidity represent normal in-home conditions, hardwood floors and furniture built with a moisture content of  6-8% is stable.

Shrinkage and Warping

1a) Arrows indicate radial shrinkage

1b) Arrows indicate tangential shrinkage

1C) Quarter sawn board with straight year rings parallel to the edges

Year Rings:  Each board has a unique year ring pattern (grain), dependent upon its position in the log.

Shrinkage and warpage vary with wood moisture and with the arrangement of year rings.

Shrinkage:  Whenever wood below Fiber Saturation Point looses moisture, it shrinks. By actually measuring the shrinkage in a block of wood, it has been found that shrinkage is not uniformly the same in all directions, but differs with the grain. Tangential shrinkage along the year rings is twice as much as radial shrinkage across the year rings. The different shrinkage factors within the same board cause warping by pulling the board in different directions.

Warping: In most cases shrinking is accompanied by warping. Warping deforms boards by cupping, crowning, bowing, twisting or a combination of all four.2a)   2b)    2c)   2a)    Twisting: Curved diagonally across the board2b)    Bowing: Curved along the length of the board

2c)    Cupping: Curved downwards along the width of the board                                           Crowning: Curved upwards along the width of the board. The drawings above indicate the main deformations of a board. For instance, when a wood floor gets excessively wet the floor planks absorb extra moisture and swell. Since there is not much room to expand problems become obvious very fast.

How Seasonal Changes in Humidity Affect Wood.

When wood is exposed to different temperatures and different RH of the air it will either absorb moisture or it will lose moisture. Thus, with the changing seasons wood can absorb or lose moisture. EMC is Equilibrium Moisture Content. The EMC is what the moisture content of the wood will be when the wood will not lose or absorb moisture due to temperature and RH. RH has a much bigger effect on wood than temperature. Click here for a table. The following are different scenarios that occur during the seasons:

Summer, Hot and High Humidity:

 With high RH and high temperatures wood will absorb moisture.  Wood always want to be at an equilibrium with the air. If there is a lot of moisture in the air the wood will absorb moisture until the EMC is reached; glue lines will fail, wood floors start buckling, etc. 

Summer, Hot and Low Humidity: 
With low RH and high temperatures wood will lose moisture. 
Winter, Cold and High Humidity: 
With high RH and low temperatures wood will absorb moisture. The wood will gain moisture due to RH and lose a little moisture due to temperature. 
Winter, Cold and Low Humidity: 
With low RH and low temperatures wood will lose moisture.  This will cause the most shrinkage. 



October Newsletter 2015 Ligno-DuoTec BW in-situ probe RH test


October 2015,

Issue No. 15

Interesting Websites

The cure for concrete moisture and PH Ills

(see more)

Understanding, Preventing, Detecting and Correcting Moisture in Concrete Floors

(read more)

Keep in Touch:

PHONE: (800) 227-2105

            (503) 257-8957

FAX:      (503) 256-3844



October Sale on all Moisture Meters

Now is a good time to buy. The sale prices are good through October 31st.

Using the Ligno-DuoTec BW moisture meter for in-situ probe measurements in concrete.

The Ligno-DuoTec BW is a dual-depth pinless meter for wood floors, bamboo, and gypsum. The meter in pinless mode also gives comparative readings of concrete and other materials (Photo 2).

The Ligno-DuoTec BW meter can be used with the RH BluePeg Probes to measure ambient conditions of air and in-situ RH probes in concrete.

Image 1: Taking an RH measurement with the Ligno-DuoTec BW. Using ASTM F2170 standard. Easy and accurate measurements can be taken with a 3 mm connector RH cable.

Image 2: Pinless readings are taken when scanning the concrete surface. A great strategy to us to find where to set your probes when taking in-situ probe readings. 

However when only using the pinless moisture meter to evaluate concrete there are some major disadvantages. Any pinless meter is limited because the measuring depth is only ¾” . Moisture below the ¾” measuring depth is not included in the pinless measurements.

If problems with high concrete moisture are present a greater measuring depth is required to detect the higher moisture levels. In most cases the moisture in a concrete floor is highest 40% down into a concrete slab.  The in-depth RH Probes are able to reach deep enough to detect hidden internal moisture in concrete slabs. Flooring failure is often caused when the internal moisture raises to the surface once the concrete slab is covered.

The following photo shows all parts necessary to perform an RH test (vacuum or shop vac is not in photo)

1 Ligno-DuoTec BW moisture meter indicating RH and Temperature measurements,

RH Cable,

RH BluePeg Probes,

Sleeves (caps not in photo)

Plus attachment to vacuum inside the hole and a

Brush to clean hole before inserting sleeve.

After all parts are on site, the number and location of the measuring points is established. Each hole is drilled with a 5/8” drill bid, cleaned and brushed out. Plus the sleeve is inserted and the cap put in place before the next hole is drilled.

Each hole is drilled with a 5/8” drill bit, cleaned and brushed out. Plus the sleeve is inserted and the cap put in place before the next hole is drilled.

The Lignomat sleeves can be pressed into the hole by using your hands. Using a wooden block or a rubber mallet makes inserting the sleeves easy. The numerous ribs on the side of the sleeve and the lip on the top of the sleeve assure a tight fit, where no air from the hole can escape once the cap is in place. 

At any time after the sleeves have been set, the RH BluePeg Probes can be inserted.

The red cap is used once the RH BluePeg Probe is inserted to mark the location of sleeves, which have the RH BluePeg Probe inside.

For a pretest the probes can be inserted within an hour of drilling the holes. RH measurements after a few hours give a good indication of the moisture range in the concrete slab.

If it is established at that time that the concrete needs more drying time, the RH probes can be removed from the holes and used for later testing.

Once the cable is connected to the meter, the READ key can be depressed and the RH value is indicated. The number on the left side of the display indicates the individual RH BluePeg serial number. This allows for easy tracking of the RH BluePeg Probes.

To obtain temperature readings, simply depress the down key and the temperature is indicated.

To remove the cable, hold the black cable-end plug in place and pull on the cable. The RH BluePeg Probe is disconnected from the cable. Cable and cable-end-plug can be removed, without removing the Rh BluePeg Probe.

If the RH BluePeg Probe should be removed, connect the cable again and pull the RH BluePeg Probe out of the sleeve.

The RH Probe can be used now for further testing.

The Ligno-Duotec BW is a great meter for floor installers and inspectors. All-important moisture testing functions for flooring installations and inspections are built-in.

A further step up is the Ligno-VersaTec,  which has all features of the Ligno-DuoTec BW plus, an external electrode can be connected for measurements in pin mode. 



May 2015 Lignomat Newsletter Wireless Monitoring of Moisture


May 2015,

Issue No. 13

Interesting Websites

Cleanfax article on Lignomat Data Logging system

(see more)

Woodworking Network article

(read more)

Keep in Touch:

PHONE: (800) 227-2105

            (503) 257-8957

FAX:      (503) 256-3844



NWFA Convention

Thank you all who visited our booth at the NWFA show. We had another great show this year. Grete and Uli were very busy and really enjoyed talking to new and existing customers. 

New Website

If you haven’t already seen it we have finally launched our new website. This may have taken longer than expected however it is here and we have already gotten some great feedback. We would like to get some customer testemoials posted on our website. . Please email me at with a testimonial and I will post it on our website with a link to your site. Thank you

Wireless Moisture Monitors and Data Loggers

On-site or with remote Access

With over 40 years of experience we are one of the industry leaders in measuring moisture accurately and reliably. This knowledge was combined with the latest wireless technologies to develop the data logger BL2 series and the wireless monitoring systems.

Our monitoring systems can measure:

wood moisture, bamboo, gypsum, sheetrock, solid materials

relative humidity and temperature, DPT, GPP, EMC


concrete moisture using in-situ RH probes ASTM F 2170

Surface and interior temperature

Lignomat’s wireless systems can be used as stand alone data loggers or implemented in any control process where moisture relative humidity and temperature needs to be measured. We have been manufacturing wireless transmitters for control systems in lumber dry kilns for over 15 years.

Memo Chip BL2

Humidity data loggers provide more information than single readings from a thermo-hygrometer. Install a BL2 to keep track continuously.

–Relative humidity and ambient temperature

–DPT (dew point temperature)

–GPP (grains per pound)

–EMC (equilibrium moisture content for wood)

–Add MC Tracker to simultaneously record 1 RH probe and 3 wood
moisture measuring probes.

When humidity matters: Each BL2 comes with the high-precision RH BluePeg Probe with long-term stability. The detachable RH Probe allows for inwall, in-depth monitoring. LED lights and audible alarms can be set to indicate out-of-range values. Selectable time-interval 30 sec to 24 hrs.

The BL2 records 16000 data sets. Reports show:

Relative Humidity, Temperature, Grains per Pound, Dew Point and EMC .

Specifically for Contractors and Restoration Specialists:

For job-site surveillance and long term monitoring. Alarms can be set to alert when unwanted conditions occur. Extension cables (standard stereo cable and 3.5mm connector) allow mounting the RH probe where it can best measure and the BL2 where it can be reached easily.

Specifically for Wood: For customers concerned about wood moisture we added EMC values plus an EMC alarm. The alarm will sound when the humidity gets lower or higher than the preset alarm EMC value.

The Wireless Moisture-Log System

Allows for uninterrupted data acquisition of

 Wood moisture, Wood Temperature, EMC
 Moisture of Drywall, Insulation and other Building Materials
 Relative Humidity / Air Temperature
 Concrete Moisture using in-situ RH Probes

Reports can be viewed on-site or anywhere in the world via Internet.

Advantages of Lignomat’s Wireless System

• Accuracy and Reliability

Lignomat is one of the industry leaders in measuring moisture accurately and reliably. This knowledge was combined with the latest wireless technology to develop Lignomat’s transmitters and receivers.

• Proven technology

Lignomat’s customers have used wireless transmitters to measure and control wood moisture, humidity and temperature inside lumber dry kilns and predryers for the last 16years.

• Single and Multiple Function Transmitters

Transmitters of various combinations are available to provide solutions for the many applications, where for moisture, humidity and/or temperature need to be measured.

• Long Range Data Transmission

Transmitters can be placed anywhere within the test area. Distance between transmitters and receivers can be up to 1000 ft line of sight. Two or more receivers can be connected to reach beyond 1000ft.

• Flexible and Adaptable

Applications range from lumber drying, to restoration, to material testing in labs. Lignomat offers a variety of sensors and probes to fit different applications. All sensors and probes are detachable and interchangeable – and can be connected by cables if necessary.

• Reviewing and Reporting

Completely automatically and continuously, with a real time stamp – no time taking notes and no interruption of reporting when you are not on-site. Reports are available on-site or at a secure Web-server.

Special offer for May and June

BL2 Data logger package  Special Price – $149.00   Regular – $187.00

MC Tracker with BL2       Special Price – $369.00   Regular – $420.00