The obvious that I couldn't see. Improving drying quality

[FeltzE]

Ok, we all know it all... (we being the FF members and sawmillers in general  ;D) ...Been sawing for a million years  (22 yrs really). Have had my Nyle 200 for more than 10 years.  I am located in NC with high summer humidity and warm (80-105f) weather. ...and walked up hill to school both ways in winter with barbed wire wraped around my bare feet for traction in the ice...


Problem:  Green surface mold on SYP cut in the summer months.

Solution(s):
   (1) dip tank, nope I'm too small an operation (and too cheap)
   (2) Kiln dry that stuff... My Nyle can't seem to keep up with a 1000bf load and prevent surface mold.
    - Added small DH units to support, pulling 35+ gallons of water per day the first 2-3 days. Still getting mold
    - Nyle recommends pushing temps to max right off the bat, higher temps impede mold apparently, in the summer I have to vent to prevent overheating the unit anyway. Still mold is a problem if I try to dry the maximum load represented in the liturature.

NOTE: not an add for NYLE.... Not a hit against them. I  LOVE my Nyle unit (Not in a carnal way), Their service and sales department has been great to work with. The unit works fine I just want more...

So in screwing around last year I threw a cheap digital thermometer with a Humidity readout from wal mart up in the kiln and a spare one in the shop.  Running a load, I check the RH daily and noticed a trend. My kiln RH is/was higher than my ambient RH in the shop... The kiln wasn't keeping up with the moisture comming off the lumber (duh)... bugging me for a few days it hit me (like a runaway truckload of logs on a 10% grade).

(3) Put the darn lumber outside the door of the kiln on the kiln cart, and put a pair of my 36 inch shop fans on it for a couple days. 

The shop fans should be cheaper to run than the kiln unit plus the 3 circulation fans inside and I'll use lower humidity air (ambient air) to pull that "free moisture" off the wood. Then finish in the kiln

Yup That worked just fine and saves me a little money even though I don't dry that much pine, I do get a call for it occasionally.  8)

I suppose as an after thought that another possible solution would be to plum 80f or warmer ambient air from the outside of the kiln through the Nyle DH unit lowering the RH of that air, and venting totally from down stream of the lumber maximizing the reduction in humidity for the first couple days then closing the intake vent and going to a "closed" system to finish.

Well I'm too cheap for the new duct work... there ya go

[GeneWengert-WoodDoc]

A fan shed (pole shed with open sides) and some fans, stationary to portable, would be ideal.  There are some pictures of such sheds in DRYING HARDWOOD LUMBER; the info applies to softwoods however.

Here is my evaluation:

#1 does indeed not work for small producer.  You want a chemical that will not carry over into the planer shavings or the final product.  To use the approved treatments is expensive, especially on the small scale.

#2  The mold needs high humidity and liquid water to grow.  A small DH (L-200) will not remove moisture very fast from the air, as the SYP is putting more moisture into the air ASAP.  You could decrease the amount of wood in the kiln so the moisture load would be less, but that also means less output per week or month or year.  Plus that would not help if you sawed more footage than fit into the kiln.

So, #3.  Keep the rain off the lumber and have good air flow.  Your warm climate means that your risk is much higher than further north.  Plus syp is harder to dry than white and red  pines that we have up north.

[red oaks lumber]

air dry the lumber first, in an area that has awesome airflow. the 3 biggest things for reduced molding on green lumber.
1) air flow
2) air flow
3) air flow
if you can supply that location, you'll see good results. if that isn't an option redo your kiln baffle and put a total of 5 kiln fans , i did this on one of my l-200.the increased air flow was very noticable with good results.
you could also piggyback another kiln compessor, doubling your drying speed. i also did that with one of my chambers, i could load 5,000 b.f.  green pine and dry it fast and no mold. there isnt much that cant be done if you have an outside the box thinking

[just_sawing]

I am a firm believer in power washing green lumber. This removes surface sap and the water that you put on it is easily removed in the drying process. This also seems to relaxe the wood to accept the stack without as much bowing.   

[longtime lurker]

Apply a borate spray to the timber when you strip it out. Same mix of 60/40 borax/boric acid as a dip tank would use, but just sprayed on to the point of getting some runoff... and spray the stickers as you go. Then strap it and turn the fans on... it's enough borax to impede fungal growth on the outside without actually being a borate treatment.

(Just turning the fans on often means you'll get mould growth in strips under the stickers where the airflow isn't getting to the timber surface)