Case Study: Customer
Calls with Floor Covering
Failure
We recently had a customer call us with a problem. He was called onto a site where the floor had cupped and boards were twisted. He wrote us that he inspected a wood floor, ¾ x 5 inch, stapled down, upstairs over plywood. Consumer told him the species was Teak. The ¼ and ¾ depth readings were done with a SDM, species setting 55.
While writing the report, he called and found out from the floor reatiler that the species was Timbauba. The product name for the consumer was Golden Teak. So he do not know how to adjust the meter readings.
Location 1/4″ depth 3/4″ depth
Hall 12.4 12.4
Hall 10.9 11.1
Bedroom front 10.1 10.4
Front closet 11.9 12.3
Hall bedroom 11.1 11.3
Master 10.2 10.7
Shelf 12.8 12.8
Shelf 11.4 11.6
Pieces of wood sent in by customer to be evaluated. The wood as shown above was warped.
Grete Heimerdinger’s response – VP Lignomat
here is a web-site which has information about Timbauba http://www.fpl.fs.fed.us/documnts/TechSheets/Chudnoff/TropAmerican/htmlDocs_tropamerican/Enterolobiumschomburgkii.html
The specific gravity for Timbauba is very different from 55, that is why those measurements came out so different. The low Lignometer K readings indicate that the meter was giving default readings, which means the resistance in the wood is so high, that the meter cannot measure the wood.
The SDM readings were corrected for setting number 55. To see the difference in readings between 55 and 84, I took a piece of White Oak and measured the moisture on setting number 55. The readings were about 11.1, 11.0.Then I changed the settings to number 84 and took readings again of the same White Oak piece in the same location and the measurements showed 6.9 and 7.0. Changing the setting from 55 to 84 will reduce the measured values by about 4%. I hope this information helps. Let me know, if you have any more questions.
Grete
When taking measurements of a piece of wood it is crucial to have the proper calibration for the species of wood to be tested.
When using a pinless moisture meter the specific gravity is the calibration factor. With Lignomat pinless moisture meters you simply put the specific gravity into the meter. For example: Specific Gravity of Timbauba is 0.84 so the Ligno-Scanner moisture meter should be set to 84.
The calibration for a pin type moisture meter is a little more complicated. Lignomat performs an oven dry test to find the appropriate calibration for the wood. When you have a moisture meter with 2 wood group settings all woods are put into those two settings depending on the oven dry results. When you have a moisture meter such as the Lignometer K which has 150 different wood groups there is a much finer calibration so you will get a more accurate reading depending on the wood species.
Lignomat offers free oven dry testing for any wood that we have not tested in the past.
For this case study we did not have a setting for Timbauba so the inspector was asked to send in a few pieces of wood no more than 6″ long so that we could establish the proper Lignometer K setting for his wood.
After the oven test the results were as follows:
Warped piece of wood measured 8%
Unwarped piece measured 8.7%
This obviously shows that the readings that were taken with the wrong settings were inaccurate. After the oven dry test is done a calibration for the moisture meter is established.
Nobody needs to wonder why the warped wood tested with such normal moisture contents. Lets assume the wood floor was delivered, not tested, and installed at a higher moisture content than 6-9%. As the wood dried out, it warped and then when tested it showed the right low MC.
Make sure to give Lignomat a call if you are having problems finding the correct wood species settings. We can help.
800-227-2105
sales@lignomat.com
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