I would like to retard moisture change of plywood. The plywood has Maple/Birch decorative veneer with softwood core.

Based on internet research (mainly Gene Wengert's past response on this forum), it seems I have two options: 1) Vapor resistant finish, and 2) Plastic wrap.

Below are my questions:

1. What exactly is a “good vapor resistant finish”? What chemical composition or brands do you recommend?

2. Is the “vapor resistant finish” the UV clear coat commonly used on prefinished plywood?

3. Should all plywood surfaces (including the four edges) be sprayed with this “vapor resistant finish”?

4. As for plastic wrap method, what is the minimum thickness and type of plastic?

5. Should the plastic wrap be in the form of stretch wrap or gusseted plastic pallet bag?

6. What is the proper way of wrapping plywood to minimize moisture change?

What is you end goal? Stabilized shipping of raw material? Storage? Finish coating?

My goal is to stabilize the plywood for shipping (from plywood mill to my warehouse, then to UV contractor) and for storage in my own warehouse.

I am located in a dry climate and the plywood is coming from a wetter climate.

Say you put it in a Ziploc bag, no moisture loss from the humid mill, to your dry shop.

Whay happens when you open the bag, and cut parts?

I feel like you want acclimation, not isolation to your environment.

What are other plywood exporters doing? They have millions invested in product and will have done the homework to protect their product. No need to reinvent the wheel

The assumption is your trying to stabilize import material that is going haywire who knows.

Bottom line I would guess is the only viable option is to 3 wrap ths units (clean folded sheet below, one on top, and a boat-style shrink wrap band is the only cost effective option. Any type of coating protection is only viable if its part of the fibal product (cost)

Please see the map below for average RH and MC for interior woodwork in various parts of the US. I have also attached a chart that shows RH and corresponding MC.

My workshop is located in Southwestern United States. Target MC for local orders is 5%.

I don’t have much experience with plywood. My company specializes in glossy contemporary lacquered doors and particleboard carcass. Recently, I have customers who strongly prefer plywood carcass and hence I am pressured to offer plywood carcasses.

I don’t import plywood from abroad. The plywood I plan to buy are produced in the Pacific Northwest. The UV contractor is also located in the Pacific Northwest.

I usually have my UV contractor picks up the plywood directly from the mill. He has found out that plywood's MC is always at 9-11% when he inspects at the mill. Because of the huge difference between 11% and my target MC of 5%, I worry that the plywood would warp when they arrive at my climate.

Questions:
I have read from Gene Wengert’s post on another forum that “When softwood plywood is manufactured, it would be typical to find 4 to 5% MC, as the heat used to cure the adhesive in a press tends to drive off the moisture. “

1. Based on this info, can target MC of 5% be achieved if the plywood mill is willing to wrap the plywood with plastic?

2. I don’t know how quickly moisture change occurs. How soon does the plywood mill have to wrap up my plywood with plastic?

3. After my UV contractor in the Pacific Northwest finishes clearcoating the plywood, does he have to package my plywood with plastic in a low-humidity room with 25% RH? How soon does the UV contractor have to wrap up my plywood with plastic?

4. It is likely that the plywood mill doesn’t want to change any of its usual packaging procedure. In which case, how should I acclimate my plywood?

Tom- I wonder how plywood mills in Oregon and Washington manage to sell to Southwestern states such as Nevada and Arizona. Do you know if it is common practice for plywood mills to produce 4-6% MC plywood for the southwestern market?

Mark- Thank you for suggesting the 3 wrap method. The plywood mills I am considering are located in Oregon and Washington.

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Thank you for your reply, Karl. Your response has given me a lot of think about.

My company specializes in glossy finish. I only sell assembled cabinets.

My customer base is people/businesses in skyscrapers in LA, Las Vegas, Phoenix and Miami. The plywood mill I plan to buy from usually produces plywood at 9-11% MC.

I plan to take the plywood out of the plastic bags only when I need to cut the components. The components will be cut by CNC in my shop’s general area (which has the local dry humidity of around 25% RH).

I have not decided if I should go for isolation or acclimation.

If the plywood mill wraps up the plywood when the MC is still at 5-6%, then maybe isolation is the better idea?

If the plywood mill only sells their usual 9-11% MC plywood, then acclimation is my only choice.

I have given this a lot of thought and I don’t know if I am getting paranoid. I may have been overthinking.

Now I have even more questions in my head:

1. Since I have customers in humid Florida (target MC of 11%), should the UV contractor in Oregon wrap plywood for Florida in plastic, so that plywood’s MC won’t decrease rapidly when it gets to my dry shop?

2. For storing cabinets going to Florida, should I humidify a closed-off room in my shop that matches Florida’s target MC of 11% (i.e. 58-63% RH), and have packaging occur inside this special room?

3. Is packaging in a special humid room necessary, or is packaging in shop’s general area good enough?

Buy the shrink wrap they use to store boats over the winter. Wrap and shrink with a propane torch.