The moisture meter reads 8.3% on air dried wood

[WoodenHead]

I recently bought a moisture meter (J2000X Delmhorst).  I thought I would try it out the other day on some white Ash that has been air drying for about 3-4 months.  I cut a piece in half and probed in the middle (after setting the meter to ash) and was suprised to get a reading of 8.3%.  So I tried another piece and read 9.6%.  A third piece was around 8.6%.

Do these readings make sense?  The pieces are light enough and it has been very dry lately.  I was aiming to dry the ash to about 8%.  If the moisture content is at 8% (according to the meter) is there still value in throwing the load into the DH kiln? 

[Den Socling]

There is a temperature adjustment on the J2000 as well as the species selection. Did you adjust it? Your readings sound very low.

[Larry]

Did you check calibration first?

I have two meters I check against each other and against an oven dry sample every once in awhile.

One meter consistently reads 1% high.  Its my Wagner pinless, but not a problem so long as I'm aware of it.

[WoodenHead]

I followed the instructions for calibration, for temperature correction and for species.  The 8.3% measurement was the result.  If it sounded too low I was going to try an oven dried sample. 

[WDH]

We can't get that low on air dried wood here, but this is not Ontario.  You would need an extended period of time with the relative humidity in the 30 - 35% range for the wood to air dry that low.  Is that the case?

[WoodenHead]

The weather has been extremely dry this summer.  We had less than a 1/2 inch of rain for the month of July.  The later half of June was also dry  After a little bit of rain at the beginning of August we've had another couple weeks of dry weather.  Farmers around here are having a tough year.  One guy was telling me that they were excavating an area, digging deeper than 6 ft in the ground, and the soil was dust.  Normally it isn't this dry around here.

But, to answer your question, I'm not sure that we have seen 30-35% relative humidity for great lengths of time.  Hard to say without accurate equipment.

The other thing I have noticed is that the outer edges of the wood seem to have a higher moisture content than at the center.  I have read up above 10% in some cases.

[Norm]

The lowest I can get my air dried lumber is inside a insulated metal building during the winter and that's 9-10% with cherry and walnut 4/4.

As dry as it's been this year you may be accurate.

[Larry]

Here is a Equilibrium Moisture Content (EMC) Chart.  I printed it out on heavy weight paper and have it in the shop. 

To keep track of the rh I use a low cost Radio shack indoor outdoor rh meter.  I check the meter every morning.  After a while I can pretty much tell you without checking, what the mc is of a stack of air drying lumber.  The actual reading doesn't mean much since rh varies so much from night to day...its the trend over say a month.  Also helps monitor lumber in the shop.

[WDH]

That is a very helpful chart.

[WayRiver]

Newbee...u should be able to check the site WeatherSpark.com for historical RH in Toledo.  (several days this summer in the 30 to 40% range...couple days in the high 20%) (you will need to call up the humidity graph)....yep its been a dry summer

[Tree Feller]

Where and how the lumber is stored can greatly affect the dryness, too.  I know it isn't unusual in the summer around here to see 85% RH at daylight and 30% or lower at 3:00 p.m. outdoors. I don't see those high values inside my shop (thermal hygrometer on the wall inside) so the lumber stored there doesn't have an opportunity to absorb as much moisture from the air. Kiln dried lumber will retain it's MC in my shop (air conditioned).

BTW, that's one of the advantages of a solar kiln. The fan is normally on a timer so that it shuts off around dark. As the darkness cools things down, the RH inside the kiln rises and the moisture effectively "conditions" the lumber, relieving the stresses introduced during the drying process.

[Knute]

It has been so dry here this year my air dried oak is at 8%. Usually can't get it below 10% to 12%.