Q: We will store assembled, finished bath vanities and medicine cabinets in cardboard cartons in an unheated warehouse throughout the coldest months of the year (below zero). We do not know what amount of stress this will have on the wood of our product. We are also worried about condensation build-up. Your thoughts?
A: Wood does not shrink or swell with changes in temperature. So, the cold is not a problem. Also, the water in wood at less than 30 percent MC is not liquid, so it cannot freeze. Further, most adhesive joints today used on wood also can withstand cold without changing their properties. (Uncured adhesive often is harmed by freezing temperatures. Application temperatures also are usually required to be warm.)
Wood, however, does change size with changes in relative humidity. So, you need to monitor this in the storage area. As most houses and offices will have an RH in the winter of about 30 percent (some are drier), you need to maintain the warehouse at the same RH, on the average. You can do this with a black painted roof. Heat the inside a bit and the RH will automatically decrease. You could also use a house-type dehumidifier to remove excess moisture in storage (if any), but that is more expensive. Note: If it is not sunny enough, then add a little heat inside the building; control the heat with a humidistat. If it is too humid, then add heat.
In order to get condensation, you need a source of moisture. Where is the water going to come from? If you have leaks, fix them. The warehouse needs to be fairly tight. Alternatively, use plastic to create a "tight" room within the warehouse. To change the MC of 1,000 BF of wood by 1 percent MC requires about 4 gallons of water. That is a lot and would not come into the warehouse if the doors are tight with no leaks, etc. Wrapping your products in plastic will help in the short run, but unless the wrapping is fully sealed around the product, wrapping won't help in the long run (a week or more). There is just no shortcut for monitoring and controlling the RH for wood products in storage.
One other thought: Make sure your finish will pass a cold test; that is, no crazing.
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