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kiln drying sinker Caribbean heart pine1/14
I am three years into a project in Nicaragua, recovering 100 year old, old growth logs. We have just completed constructing a 25,000 bf capacity kiln. The boiler is fired with wood scraps, and we circulate hot water through large radiators to extract the heat. I have never dried wood, and I need help and advice on drying river recovered old growth Caribbean pine (very similar to river recovered long leaf pine.
Can you control temperature accurately? Humidity? Air velocity?
What thickness? What width?
Do you have a final target MC and how close must all the pieces be to the target? Can some be too dry or too wet?
Were they in salt water or fresh? Flowing or mostly stagnant?
Do you have the Dry Kiln Operators Manual?
Hi Gene,..thanks for your response and questions. We will be initially drying 4/4 with random widths and lengths (see pics) I have read everything on Woodweb, that you have written on kiln drying pine, setting the pitch at 165 F. , also I understand a little about the wet bulb differential (5 F. optimum ) and dry bulb. We have been shipping our wood to Managua to dry, and it is expensive and time consuming. I have a Nicaraguan worker, who worked for a large lumber operation called Madensa, here in Puerto Cabezas. They went bankrupt after 2008 and I bought the kiln from them and the boiler. This worker has extensive experience drying hard woods, but not the pine. The two kiln chambers have four vents each, they were connected to operate automatically, but now everything is manual. We built a valve system to regulate the hot water flow to the two separate chambers. Also I have simple temp gauges we can monitor from the outside, using a restaurant thermometer for making coffee lattes! This area is very remote and difficult to buy parts. I would like to dry our pine very slowly and carefully. Most of the wood, has been air drying for two or three months. The MC ranges around 25%. The boards are random width 3" to 12" in width and 4' to 12' length....all is heavy cut just over 1". What I have heard from the companies that have been drying my wood, is the lighter resin content comes out of the kiln around 9% but the heavy resin content shows around 13%. I would be pleased if we could reach those MC's. We fired the kiln the other day and brought the temp in one chamber up to 140 F. in 45 minutes. Our wood fired boiler is way oversize for the 25,000 capacity kiln. Regarding the Dry Kiln Operators Handbook, no I do not have it, and I will source it and read it.
Gene, I just went up to our mill and air drying area, and I am very surprised at the MC of our 1" milled wood. In the previous message I said the MC was around 25%. It is not. It was between 14% and 11%. I used two different two pin moisture meters. A Ligomat mini-LIGNO E/D and a General MMD4E. They are not very expensive meters, however they both confirmed the readings. Also I downloaded the Dry Kiln Operators Handbook....excellent...thank you!
At this low MC (under 25%), your only concern is drying the wood too dry...that is, over drying. If you go under 10% MC, the cup increases and the machining becomes poor.
I would start the kiln at 130F. I would keep the vents closed in order to achieve around 10% EMC. THen, after a few days when the wettest pieces have dried to 13% MC, increase the temperature to 165 F at 10% EMC with the vents closed for 12hours to kill any insects.