THE LIFE OF A SLAB
A professionally finished wood slab can be beautiful, magical, sci-fi like with 3D effect, etc… Although so often admired, not much thoughts have been dedicated to the creation process of a re-purposed wood slab. From cutting the tree to the completed project, though there are multiple steps in between, we can basically break down the process into these four principal phases:
Logging is the activity of cutting, skidding, on-site processing of trees or logs and loading them onto skeleton cars or trucks to be transported to a sawmill.
“In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard. However, in common usage, the term may be used to indicate a range of forestry or silviculture activities” – (Wikipedia).
Ponderosa Woodslabs are from urban reclaimed trees that are locally harvested to be re-purposed for beautifully crafted projects or furniture.
MILLING / CUTTING OPTIONS
Milling is the process of turning the log into lumber for various projects including cabinetry, countertops, bar tops, furniture, DIY projects, etc… At the sawmill, the logs are placed on a Band Saw and sliced into slabs. The Band Saw can be adjusted to achieve various thickness for the slabs. Also the logs can be cut length wise (top to bottom) with the Band Saw, or cross-sectional with a chainsaw to create rounded slabs. If all the barks are sliced along the length of the log, the result is a rough square blocks which can be cut into “Square Edge” Wood Slabs. If the barks are left untouched, the wood slabs are referred to as “Live Edge” and also known as “Natural Edge”, which is a style of woodworking where the natural edge of the wood is incorporated in the design of the furniture.
When it comes to cutting a log into slabs, one of the most important features of a Band Saw is its blade width capacity. A small sized Band Saw is restrictive in cutting logs that are large in diameter, which respectively corresponds to the width of the slab.
Ponderosa Millworks which provides a bulk of our slabs has a full Milling Operations including a Wood-Mizer 1000 to slice logs up to 6 feet wide.
After the logs get milled into planks or slabs, the end result is a stack of wet wood with an average moisture content of about 32 percent. Before the wood can be used, it needs to be reduced to a moisture content of about 7%. Therefore, the wood must be dried using one of two methods: Air-dried or Kiln. Wet wood or improperly dried wood is proned to cracking and warping.
Air-drying wood is a very slow process, but the simplest and least expensive method between the two options. It basically involved leaving the wood to be dried naturally in the open air, although the process itself can be [somewhat] more complicated that it sounds. There are a lot of factors to consider with air-dried wood including stacking the wood properly; sealing the ends; keep it protected from the elements (i.e. direct sunlight, rain); stickering to create air space in between the slabs and prevent them from twisting as they dry. The length of time required to air-dry a slab varies greatly based on the initial moisture level; the species of wood; ambient conditions, density, and thickness to name a few. As a rough starting point, the rule of thumb is to air-dry for about one year for every 1-inch of thickness.
Kiln Dried Wood
A faster way to dry wood is by using a Kiln, a well insulated room or container like space which provides heat and dehumidification. It removes the moisture that the wood is giving up by maintaining a temperature of about 120 degrees Fahrenheit. The amount of wood placed inside a Kiln depends on the wood species being dried. Careful attention is placed on the moisture content level of certain wood types for the dehumidifier to be able to handle the load. Kiln Drying can cut the drying time significantly. What takes 2 -3 years to air-dried can be accomplished within 2 – 3 months with a Kiln unit, and with a more evenly and uniformed drying cycle.
Once the wood slabs have been dried and achieved a moisture content of about 6%, they can now be used for their intended purposes. However, they still have to undergo a few preparations before they are completely ready for project application. Although some wood slabs retain their straight planed surface and can be sanded and finished, some slabs may end up with warped and uneven surface. The three basic tools that are used to surface or flatten a wood slab before applying a finish on it are: The Jointer; Planer; and Sander.
The first process in surfacing (flat straight surfaces) a wood slab is to flatten one face of the slab with a Jointer, which is a machine with a cylindrical cutting head (knives) between two parallel tables, an infeed table (right side) and the outfeed table (left side). The infeed table is set at a height lower than the outfeed table, and the difference in height (adjustable up/down) is equal to depth of cut that the jointer is set to shave off the surface of the slab. The outfeed table is set at the same height as the cutting head.
Next up… The Planer, which also has a cylindrical cutting head. Before going through this process the slab must already be totally flat on one side, since the planer’s job is to cut a flat surface parallel to its own table. Therefore any imperfection on the opposite side will replicate on the side being planed. The Planer does not require a smooth surfaced slab, just a perfectly flat surface to work its magic.
Now that you have two evenly flat surfaces (faces), the slab is now ready to be sanded and prepped for the finishing touch with either oil, varnish, lacquer, etc… Depending on how rough the surface of the slab after planing, a 40 – 60 grits can be used to begin the sanding process. With a smooth surface, 150 grits will get the slab surface close to a ready state for finishing application. Typically, the sanding process is completed with a surface that is sanded with grits between 150 – 220 ratings… However, a higher grit number could achieve an even more lustre outcome when done in between applying different coats of the finish.