Aloha Fine Woodworking colleagues,
We have several eucalyptus (eucalyptus robusta) and java plum trees (syzygium cumini) on the property that are coming down to make room for a driveway and replanting with native koa and sandalwood.
Our plan is to (Alaskan) mill the logs and make floorboards from the eucalyptus and boards for all sort of garden projects from the java plum trees. I plan to set up a solar kiln similar to that of Brenon Plourde from May/Jun 2024 issue. Our microclimate is best described as “rain forest” at an altitude of about 800 ft above mean sea level.
I am posting because I haven’t been able to find anything about drying rates on drying for either wood. So I am looking for advice from anyone who has tried and tested solar kiln drying or even simple air drying.
Last but not least, I haven’t found material/mechanical properties for the java plum wood, except that is somewhat of a hard wood and water resistant after kiln drying. Does anyone have more details on java plum wood.
Mahalo.
B
Replies
Will the eucalyptus and Java wood be kept outside for those garden projects you mentioned? If so, you can prolly just air dry them outside at a year per inch of thickness. The solar kiln might be over kill for wood that will remain in the microclimate.
@elmaduro, thank you.
I will start with air drying everything. Looks like a shade cloth or similar wrapper with a "rain proof" top is the way to go.
The eucalyptus will go inside the house where we'll have AC. The Java plum will stay outside and be used to build anything from a shed to chicken coops.
Agree with Confusius on covering the stacks while air drying. This will shorten the time. If you're in a windy area, then the shade cloth will help.
End coat the logs immediately after cutting to help prevent end splits and checks. These will extend during drying. Re end coat the lumber if you trim to length after sawing.
Skolman air dried E. robusta to 20% MC in 2.5 months - June-July in Hilo (paper attached - Skolman. 1964. Air-drying of Robusta eucalyptus lumber).
E robusta is more prone to c0llapse and checking than E. saligna and E. grandis. Airdry to 30% MC (lower is better but getting to 20% may take a long time in your climate). It helps the kiln drying stresses if the core of the board is below fiber saturation (30%)
Then do not get it too hot in a kiln. Keep the temperature under 100 to 120 F until the wood is under 15%. After that, raise it if the kiln is capable.
If drying to, say 9 0r 10% for your air-conditioned space, you will need to store the KD lumber where it will not gain moisture. Stored lumber in HI can quickly go up to 16%.
This paper provides a few comments but was too large to attach. You might be able to google it.
Skolmen, R. G. 1974. Some woods of Hawaii: Properties and uses of 16 commercial species. USDA
No drying info, but you might find this interesting
Skolmen, G.G. 1963. Robusta Eucalyptus Wood: Its Properties and Uses. U. S. Forest Service Research Paper PSW.
Forest Service GTR PSW-8.
Mahalo, MRM97330.
The articles you attached and the one you cited are very useful. Indeed, the graph in Figure 2 of Skolmen, "Air-Drying of Robusta Eucalyptus Lumber," tells me that I should be grateful to get below 30% MC by air drying the robusta. We do occasionally get so called horizontal rains during late "winter" that I'm sure will mess with the drying.
Do you have any advice on coats/sealants? A search on google gave me at least a dozen options ranging from latex paint to expensive name brands. My only experience is grandpa's using his own recipe of beeswax solution in water for white oak, mulberry, etc, but in a temperate climate.
A latex paint help. Roof tar is also works and is probably better. A wax-based sealant works better if kiln drying below its melting point (often 130-140F). UC Coatings' Anchor Seal is an example that is common in the hardwood industry. I used to use a neoprene paint for research work, but it's too expensive to be practical. Don't do this, but epoxy with aluminum foil is the ultimate barrier.
The idea is to slow drying from the end grain. Years ago, but rarely now, producers would put burlap over the ends of lumber stacks and keep the burlap wet during the hottest part of the day. Shade dry is used on the ends of units to reduce airflow and moisture loss from the ends of the boards. It's easier than coating, but less effective.
Whether any of this is done is determined by the value loss from the end splits and end checks versus the cost of the treatment.
Mahalo nui loa, MRM97330.
I am converging to either latex paint or roof tar. Based on the size and quantity of logs, I will have to compromise between upfront costs of sealant and losses due to end splits and end checks.
On the mainland, the home improvement store in our village used to (practically) give away leftover latex paints and primers. I'll check the ones on our island and report back here. I hope to get a few good photos and post them here as well.
Aloha.
For what it's worth...you won't have to remove the latex paint when you start your milling process. Your machines won't like the roof tar as much. It's entirely possible that you'll wind up cutting off the ends that you are now trying to save just to avoid removing the tar.