Over the last 20 years the impact we have on tropical forests around the world is becoming more and more evident.  As a woodworker and environmentalist it has always been important to me to try and have the least negative impact on the world around me, considering both humans and nature.   I read all that I can find on the subject and speak to people on both sides of the issue, namely the woodworking industry and the environmentalist organizations.  I am not looking for justification in using the woods I do, just the truth about the impact of my use.  My research so far has come to several conclusions.

The best that I can find is the tropical forests around the world are being destroyed at an alarming rate.  If nothing is done, this will have world-wide implications.   People in government will tell you the reasons are complicated and varied. 

The truth is not so complicated as politicians would like you to believe.  Basically third world and emerging country’s populations are growing at alarming rates.  These country’s populations are expanding into the forests around the cities and towns to live, using firewood for heating and cooking, and subsistence farming.  The governments encourage this encroachment because cities are overpopulated and they see the forest land as a possible agriculture bonanza in agricultural exports (cattle, soy corn, etc) that they need.  These countries around the world are so desperate for foreign money they choose to ignore the long-term consequences of not regulating forest policies and working on stabilizing population growth.  Both religious and cultural influences, whether domestic or foreign, also prevent concrete steps from helping to stabilize populations.  Forest destruction is by far a result of agricultural business and human population growth, not by cutting trees for wood products or lumber.

But what is also true is that this relentless deforestation starts with legal and illegal lumber companies building roads into the forest to cut specific trees, then the subsistence farmer enters the forest on these roads and burns down the trees and vegetation that is left.  They grow crops for a few years, then move deeper into the forest burning down more forest, with cattle ranchers coming in right behind them.  All this is with the explicit, although sometimes covert, consent of the government. 

All this said, I have put an emphasis on using domestic woods where forest stewardship has long been practiced, and buying tropical woods from suppliers I know and trust, even though this is probably having no impact on tropical forest destruction.  This problem can only be solved by the world working together to educate and stabilize world populations.

In my last blog, I spoke about how tropical woods change color and now we will talk about domestic hardwoods and how they change as they age.  Again, there are too many woods to list them all, so we will talk generally on how they change depending on direct and indirect UV exposure.

Domestic woods are completely different from tropical woods in how they react to UV light and oxidation.  Generally they lighten only, becoming more yellow or golden.  The only exception I know of is cherry, which like tropical woods, darken with direct or indirect light.  Cherry does switch gears after about one year, and will lighten if it is continually exposed to direct sun.  But if it only gets indirect sun, it will continue to darken.  Black walnut, on the other hand, starts out deep purple brown and lightens to a light golden-honey brown in 2-5 years with indirect light and much faster with direct light.  Light-colored woods, such as white oak, birch, and maple all yellow or become more golden-light nuances of color.  Slight greens, pinks and browns tend to soften and variations in color become less, so that color matches improve over time.   Again, the exception is cherry.

Cherry, like tropical hardwoods, should be matched not just for color but also for density and grain.  Typically 1st growth cherry will be heavier (denser) and will deepen in color much more than the 2nd and 3rd grows.  Also, solid cherry or walnut used next to a veneer of the same species will look quite different five years out.  But in most cases using light hardwoods, the variations between solid and veneer are small, with the solid wood usually becoming more golden over time. 

Knowing how woods change allows you to plan your wood species and finishes for the best results now and into the future.

Whether you’re going to make something in wood or have someone make it for you, at some point you need to decide on the type of wood for color, texture, strength, etc.  So, I am going to talk about some of the things you should consider when selecting the wood for color. 

Wood is consistently changing color no matter what finish you apply.  Clear finishes, especially, change color over time, but a heavily-pigmented stain or tint will change also.  Direct sunlight has the most pronounced effect, but even rooms with only North-facing windows receive indirect light which will have an effect on color.  The idea is not to pick a wood for  it’s color when first milled, but for what it is going to look like in one, five, or ten years.  Otherwise you might be very disappointed. 

I can’t list every type of wood here, so I’ll give some general changes you should consider.  Almost all tropical woods (woods growing close to the equator) become darker, even with direct sunlight.  Some become very dark.  Also, in some species, the degree of darkening will vary quite a bit from board to board.  You may mill the wood, select color matches, and one or two years later the match is not even close.  When matching different boards for color you need to select for color, texture, and density (weight) to make sure the color remains matched over time. 

UV finishes will only slow this darkening and lightening process down between 10% and 50%, but not stop it.  If the tropical wood piece is getting only indirect sunlight the wood will only darken.  Most tropical woods have bright distinct colors when first milled, but as the darkening occurs, the purples, reds, pinks, and greens usually become less bright and more brown.  Purple heart, for example, will be completely dark brown in a few years with no purple.  Burmese teak, when first milled, is very light tan with pinks and greens.  Within days the pinks and greens are gone leaving an even light brown, becoming more and more golden medium brown over time.

All woods change, and that is part of their beauty.  Knowing what that change is going to be eliminates the surprise and allows you to enjoy this natural process. 

In my next blog entry, I am going to talk about domestic hardwood color changes which are very different than tropical woods.

There are a number of different criteria I use to decide on the type of glue to use for different applications and I would like to talk a little bit about that in this blog.  Exposure to the elements (inside or outside use), density and oil content, color, stability, and use of end product.   Below is a partial list of common glues I have used in the past.

1.  Plastic Resin (water and powder mix).  This glue is too brittle and I don’t recommend using it for any circumstances.

2.  Urac (powder and resin mix).  A urea-formaldehyde glue.  It’s very strong, has good gap filling qualities, and is good for exterior use.  It comes in second place to Epoxy for oily/dense woods.  Wear gloves and mask when mixing.  I have replaced it’s use with Titebond III which has a very low toxicity level and is just as strong and versatile for interior use.

3.  Gorilla Glue (urethane glue) is very strong but because of foaming I don’t use it when other glues are as strong and much easier to work with.

4.  Resorcinol (powder and resin mix).  This leaves a dark glue line, and has all the same good and bad qualities as urac.  I use epoxy in its place now because of more versatility.

5.  Epoxy (liquid hardener and resin).  I mostly use West Systems for exterior use, dense oily woods, and in the vacuum press for bent laminations (epoxy doesn’t need air to cure).  It is very toxic and care must be taken when using it.

6.  Titebond III (yellow or tan, water clean-up)  I use Titebond III by Franklin on interior and some protected exterior work.  This glue is very strong, gap filling, #1 type water resistant, easy clean up, and low toxicity. 

To sum up the above, I use two types of glues now.  West Systems Epoxy on exterior heavy-exposure areas or where extra strength water resistance is needed, on dense and oily woods like teak and rosewood, and in vacuum press bent laminations.  And Titebond III on interior work.

West Systems requires special pumps for mix ratios.  You should apply an even coat of properly mixed hardener/resin, wait 10-15 minutes for it to soak into wood surfaces and then mix another batch of epoxy adding 20-30% by volume of colloidal silica to epoxy mix and again apply an even coat to both surfaces.   Apply a light pressure with clamps, 5 to 10 lbs.  Any more pressure will drastically reduce joint strength.

Another thing to remember - don’t use silicon lube on your machine surfaces, it will contaminate epoxies.  Thoroughly mix epoxy.  Different hardeners are available to lessen or lengthen open times.  I buy West Systems at a local marine supply store.  Clean up is with alcohol.  Always wear gloves, it’s very toxic.

And, as I said before, I use Titebond III mostly on interior work.  I don’t recommend its use for dense, oily woods.  Being water resistant doesn’t hurt, especially on bath and kitchen work.  It has a longer open time (about 30 minutes at 70 degrees Fahrenheit) which helps for the more complex glue ups.  Apply an even coat to both surfaces and not too much pressure or you’ll weaken the joint, up to about 15 to 20 lbs. is good.   Clean up is with water.  Don’t forget to wear gloves, even though its a low-toxicity glue.  This glue is a good choice where food will come into contact.

I hope I have explained the differences between glues, and you have a better understanding of the applications each type is used for. 

When making solid wood furniture you will need to glue-up a number of pieces to width to make up any panels.  Most hardwood lumber is not less than 4″ wide and not more than 14″ wide.  Anything wider has become more and more rare. 

I recently bought two Bubinga planks, 2″ thick x 42″ wide x 14′ long,  with live edges.  I can usually find woods like Cherry, Walnut, and Mahogany up to 36″ wide but these are not common sizes and take a lot of research, and  I pay a premium price for that large width.  So most work will require some glue-ups. 

There are a number of different joining methods and all require glue.  Butt, dowell, and biscuit joining are the most common today.  Also used are splines, through bolting and glue joints. 

I am going to start by explaining the worst joining methods and progressing to the best ones and explain their advantages and disadvantages.

1.  Through bolting is usually used in thicker glue-ups (2″ and greater) when making cutting boards and slab doors, for example.  It is actually worse than doing no joinery at all.  Boards are drilled through their width and all-thread is inserted through the holes, washers and nuts placed on both ends and tightened.  Sounds strong, right?  Well, it is strong, except for the problem that wood is always changing dimensions.  Higher humidity expands wood, lower humidity shrinks it.  Ten years after your glue-up the panel will still be changing dimensions with the seasons.  So when the panel expands against the tightened bolts, the panel warps because it has no where to go.  And when the panel shrinks, the bolts are doing nothing.  So what you have is a butt jointed panel which will eventually fail. 

2.  In butt jointing you are joining pieces with glue only.  With softer, more porous wood, and using all the proper glue-up techniques, it’s pretty strong because of our modern glues.  But over time, some joints will starts to fail.  With hard wood, and especially hard oily wood, the failure rate becomes higher and can be quite severe.

3.  Splines are grooves cut in the edges of the boards to be glued up.  A plywood or solid-wood spline is cut slightly smaller than the depth of the two grooves combined, for the glue to squeeze out.  Glue is placed on all surfaces and clamped up.  The glue space creates a weakness in the joint, making the joint 20% to 30% weaker than the solid wood itself.  All joinery should strive for a joint that is as strong as the wood itself, or stronger.  

4.  Both dowels and biscuits are very similar in strength but they use just slightly different techniques.  They both interlock the joint and add glue surface that butt joints lack, without causing a weakness like splines.  But they should not be used in large glue-ups or in exterior doors because of the stress.

5.  Glue joints are usually run with a shaper but can be run with a router as well.  It’s a single cutter that is offset allowing for a single set-up as opposed to a tongue-and-groove set-up requiring two cutters and two set-ups.  What a glue joint does is interlock the joint and double the glue surface, making this joint the strongest in any type of wood and without any of the drawbacks of the other joints.

As outlined above, #5, glue joints, are the best way overall when constructing solid wood panel joinery.  The other methods are widely used, but should be used with caution, and only in certain applications.  Furniture and doors should be built to last a couple of lifetimes, in my opinion, and if you build it right, it will.