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Hammered Dulcimer design, construction, and unrelated stuff

Monday, August 7, 2017

Excluding moisture exchange from wood

Wood is hygroscopic meaning it wants to absorb or release moisture based on the humidity of the environment.  Wood reaches an equilibrium moisture content based on whatever the conditions are.  In a humid Iowa summer any wood can get close to 12% moisture content (MC) in a non air conditioned home.  In winter the same wood will pretty quickly drop to close to 6% MC in a normally heated home.   When wood absorbs or loses moisture it shrinks or swells across the grain but not along the grain.  It continues to do this as long as it exists as a piece of wood.  Different species swell or shrink different amounts, but all move to some degree.  We have a coffee table that I built of 150 year old reclaimed walnut from central Illinois.  The top is 2 ft. wide, and it will swell 3/8" from winter to summer, then go back when winter comes again.  This is quite a lot, and if a wood worker doesn't plan how to construct something based on this knowledge, it can lead to trouble. 

Even plywood is affected to a degree, but since it is layers with the grain going alternating directions, it is less affected. 

In order to build a hammered dulcimer that is completely tuning stable, we learned that moisture exchange has to be excluded from the wood.  It is the shrinking and swelling that throws a dulcimer out of tune, and it can happen fast if a dulcimer that is used to one environment is taken to another that is much different.  So we did a lot of research and experiments to find an appropriate coating.  Shellac doesn't work, nor does lacquer or varnish or polyurethane.  Surprisingly, according to the Forest Products Lab the most effective coating is melted parrafin wax!  It does work, but is quite a mess!  Boat builders epoxy also works, but needs to be at least 3 coats to be effective.  Other than that epoxy paint also works, but again needs to be at least 3 coats.

Thursday, July 13, 2017

Organic Japanese Beetle Control That Works

The Japanese Beetles are horrible this year in Eastern Iowa probably due to a mild winter.  I have been using an organic recipe to control them for several years, and this year it has proven its worth.  It really works.

1/4 bar Fels Naphtha Soap shaved or grated in a large bowl.
Add 1 1/2 quart boiling water and stir until well dissolved.
Add 1/4 cup any dish washing liquid.  I use Dawn.
Stir again and let cool.
When cool put in a spray bottle and gleefully go kill beetles.

It doesn't take much, just get them wet and in a couple minutes they will be dropping off.  The soap blocks up their breathing apparatus.  Fels Naphtha Soap is in most grocery stores and farm centers, usually in the laundry section.  You have to go spray beetles every day as more come out of the ground each night.  They like grapes, fruit trees, roses, rhubarb, raspberries best, but if they are hungry will eat tomatoes, potatoes, beans, corn and lots of non garden plants like Linden trees, Virginia Creeper and Stinging Nettles.  They also emit pheromones when they find something to their liking to call in their friends.  Best time to go spray is the early morning when they are least active.

We have a big grape arbor on the front of our outbuilding, and this year the beetles were trying to clean it off.  I was right on them, though, but there were several days where there were so many they were falling like rain out of our grapes when I sprayed.  Yesterday there were probably only 100 or so, and today maybe 20.  Our grapes are a little tattered, but they aren't denuded like other folks'.  So I think we are past the big hatch and my soap spray has definitely worked.  I believe it is the only good remedy for Japanese Beetles.  Other than that you would have to spray something nasty on your garden, and you'd have to go back and do it again every day for at least a couple weeks since new beetles come out of the ground every day.  You'd have a pretty good pesticide load which would get into your food from the garden.  You'd also be killing a lot of other insects that would probably be beneficial.  But the soap you target and only get it on the beetles.  It will kill other insects, but not all.

I adapted this recipe from one in Jerry Baker's great book Old Time Garden Wisdom, and he got it from his grandmother.