Tuesday, December 8, 2009

Tech Tip Tuesday

On the WoodenBoat Forum, a member posted a thread titled "Boat Building Safety". Ostensibly it was about about the canoe that he plans to build with/for his father and was discussing a picture of Ted Moores in his Canoecraft book. The thread was intended to discuss the WoodenBoat Hat as a "safety item". It brought to mind some safety items that are all too often forgotten in woodworking in general and building canoes in particular.

Wood dust has been noted as a potentially carcinogenic material. Some types of wood are toxic, some can cause allergic reactions, and airborne dust is both a potential fire and explosion risk. If you don't believe me, take a look at this MSDS sheet from JG Architectural Supply, a wood floor vendor from Maryland. After reading it, you'll wonder why the government hasn't recalled every bit of wood grown.

For the reasons noted in the MSDS, you should always have a good dust mask with appropriate filtration to protect your lungs, nose and mouth. Also, to prevent other hazards, a good dust-collection system to deal with dust and shavings created by power tools and a circulation filter to remove airborne dust are really great ideas. They not only help to keep the shop clean, but also help to keep the shop safe. A clean shop is a safe shop.

If you don't believe me that this is an issue, consider the following scenario from the building of a Wee Lassie canoe using three 8" wide, 12' long boards, nominally 1" thick (24 board feet of stock):
  • If you start with S4S boards that are nominally four-quarters of an inch thick (really 3/4"), and use a 1/16" thick saw blade, you will turn 3.5 board feet worth of stock into sawdust ripping the stock into strips. (You turn 1 strip to dust for every four strips you cut!)
  • When you mold cove and bead features on the strips, you will turn another 4.7 board feet worth of stock into dust and shavings. (You turn another strip to dust for every three that you mold!)
  • Finally, when you fair and sand the hull before glassing, I figure another 2.2 board feet into curly plane shavings and sanding dust. (About 1/16" of thickness removed from the whole hull!)
That's a total of about 10.4 board feet that have been turned into dust or shavings in the process - a really amazing statistic considering that you started with 24 board feet of stock in the beginning of the process.

While we are discussing wood dust, don't forget that you want to be protected from all types of dust including from sanding epoxy, fillers (Like fumed silica, glass fiber, micro balloons, etc.) and varnish. When sanding the epoxy before varnish and between coats of varnish, remember that wet sanding works well and keeps the dust to a minimum.

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