|Home » Forums » Commercial Kiln Drying » Message||Login|
You are not logged in. Consider these WOODWEB Member advantages:
"white" white birch4/22
Just in the last couple of months I have been having trouble drying "white" white birch. We have had some slight sticker staining but a much bigger problem has been a blotchy browning stain happening. Not all areas of the boards are affected but many parts of the white are browning. We have not typically dried a lot of white birch so what we get often gets dried with other species such as hard or soft maple. We start these charges at 100/88 dry bulb,wet bulb. We have not had many complaints about the white birch in the past but this problem just started with a few charges for a couple months now. I looked up kiln schedules for "white" white birch in the Drying Hardwood Lumber Manual and Dry Kiln Schedules For Commercial Woods but found only schedules for low quality wood or squares that start at 140 to 120 degree dry bulb. Many years ago, when we use to dry more white birch and could fill an entire kiln with it, we started the birch at 110/95 with decent results as far as i remember. "Management" doesn't want us to start at that temp. when we mix with other white species. Any thoughts on what might help getting rid of this blotchy brown stain?
You are correct that low temperatures and a 15 depression (and make sure you actually get these) are the correct approach. As stain occurs or is set up to occur at very high MCs, get the freshly sawn into the kiln at the correct conditions within hours.
The blotchy brown stain is indeed an enzymatic brown stain found in many hardwoods that are dried too slowly and is worse with old logs and temperatures over 110 F initially.
Maybe management would be receptive to hiring a good consultant that can develop the correct operating conditions for your equipment.
The problem can come and go, so do not feel good if it temporarily goes away unless you change handling and kiln settings.
Gene Is correct about the cool temps and more aggressive depressions. Above fsp,
However, with that being said, when dealing with increasingly smaller quantities of lumber (be it logs or lumber on sticks) I feel that there is a predisposition to the development if enzymatic stain. It remains un-noticed until surfacing and no magic bullet schedule would have prevented it.
For me, I look for a differential in exterior oxidation at time of stacking. If I see the ends lighter than the middle of the board, then you are looking at old log lumber, and your chances of producing white white wood are already reduced.
Thanks for the responses. We purchase a lot of our lumber we dry from other mills in addition to our production. We often have know way of knowing how old the logs are or how long the lumber was tight packed. Just this week, we pulled a 30000 board foot kiln charge that contained MH,MS,BW,BY,CH and AS species.