Ideal humidity

O

Old-Duckman

Registered
I have an old 4.5" X 9' Brunswick Madison. I have had it recovered, new rails and pockets etc. I have it in my basement and I heat my house with a coal stove. The stove is a bit over 6' 6" from the table.

My regular furnace (elec. heat pump) fan runs constantly and I have a whole house humidifier hooked up to it which I can adjust to regulate the humidity in the house.

Currently the humidity in the basement is about 59%.

I don't want to have too low a humidity in fear of drying out the wood. In the summer I have a dehumidifier running and keep it set around 55 to 60.

Just wanted to hear expert opinion on what the ideal humidity should be to help keep the table stable and in good condition.
 
Old-Duckman said:
I have an old 4.5" X 9' Brunswick Madison. I have had it recovered, new rails and pockets etc. I have it in my basement and I heat my house with a coal stove. The stove is a bit over 6' 6" from the table.

My regular furnace (elec. heat pump) fan runs constantly and I have a whole house humidifier hooked up to it which I can adjust to regulate the humidity in the house.

Currently the humidity in the basement is about 59%.

I don't want to have too low a humidity in fear of drying out the wood. In the summer I have a dehumidifier running and keep it set around 55 to 60.

Just wanted to hear expert opinion on what the ideal humidity should be to help keep the table stable and in good condition.
Click to expand...
Best cond. for wood are around 70deg and 50-55%.
 
My trade was mostly high end wood working & niche millwork. Some of my work was routinely metered by the contractor on commercial jobs before installation. They like to see 8 - 8.5% for flooring & it should be uniform through the batch. They will take lower, prefer not higher. Definitely no hi-low mix.

I always kept the shop at 45 - 50% relative humidity (RH) when running a job. Wood equilibrium moisture content (MC) at a given humidity varies a little based on temperature as well. 50% RH is a little high for my target, but wood in process did not change much in the course of a couple weeks as received from the kilns/dealer if it was kept racked in process and covered at night. Inthe winter if heat is on full time I have to pour water on the floor at night to keep the humidity up so wood stored in the loft does not dry out and crack.

50% RH is also the tipping point where bright steel tools or exposed machine surfaces will generally tend to avoid gradual rust. So 45% - 50% always felt about right to me In the shop. OTOH I think 50 - 55% is probably fine for furniture. Aim for 50% @ 65 - 75 F temp range & life should be good. :) You are correct to avoid drying it out with the stove so close. However extended exposure to high humidity can mold & damage old veneered furniture.

Here’s a chart that shows the relationship among RH, Temperature, & equilibrium MC.

Woodworkers Source: Equilibrium Moisture Content [custom wws]

www.woodworkerssource.com www.woodworkerssource.com

smt
 
Last edited:
Ssonerai said:
My trade was mostly high end wood working & niche millwork. Some of my work was routinely metered by the contractor on commercial jobs before installation. They like to see 8 - 8.5% for flooring & it should be uniform through the batch. They will take lower, prefer not higher. Definitely no hi-low mix.

I always kept the shop at 45 - 50% relative humidity (RH) when running a job. Wood equilibrium moisture content (MC) at a given humidity varies a little based on temperature as well. 50% RH is a little high for my target, but wood in process did not change much in the course of a couple weeks as received from the kilns/dealer if it was kept racked in process and covered at night. Inthe winter if heat is on full time I have to pour water on the floor at night to keep the humidity up so wood stored in the loft does not dry out and crack.

50% RH is also the tipping point where bright steel tools or exposed machine surfaces will generally tend to avoid gradual rust. So 45% - 50% always felt about right to me In the shop. OTOH I think 50 - 55% is probably fine for furniture. Aim for 50% @ 65 - 75 F temp range & life should be good. :) You are correct to avoid drying it out with the stove so close. However extended exposure to high humidity can mold & damage old veneered furniture.

Here’s a chart that shows the relationship among RH, Temperature, & equilibrium MC.

Woodworkers Source: Equilibrium Moisture Content [custom wws]

www.woodworkerssource.com www.woodworkerssource.com

smt
Click to expand...
I remember my father air drying hardwoods cut on the farm in basements and at one time an old house on the farm. It was quite the process, took along time to get it where he wanted it. It had to be stacked for air flow with ends coated with something to seal it so as to keep it from drying out too fast. He also used an ohm meter with probes driven in at various locations to check for electrical resistance. Obviously the more moisture the less resistance. The good ole days, those old farmers/woodworkers/diesel mechanics/master gardeners from the old days knew just about all the trades, at least enough to get by.
 
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