Wood 101 // Max Taylor

5/15/2014

One of the biggest mysteries of woodworking is how to finish the final product. There is a myriad of products and processes. As architecture students in design+make, we struggled as beginner woodworkers to find the correct solution. We have spent countless hours producing solid wood tabletops from repurposed pallet wood- and they need to be able to stand the test of time to serve our client. A well-crafted piece of wood furniture can long outlast its’ maker. Shaker furniture made in the mid 1800’s in the Northeast is still available. While we don’t anticipate Hardesty Renaissance to use our work for the next 150 years, it is understood that it needs to be crafted enough to last at least decade of use.

 

In general, there are two types of finishes; on-the-surface and in-the-surface products. On-the-surface products include polyurethanes, lacquers, and shellacs. The finish is suspended in a solvent and as the solvent evaporates, the finish is applied as a thin film on the surface on the wood. In-the-surface products are penetrating oils or oil-wax blends, such as linseed oil, tung oil, and polyx oil. These oils, along with varnishes, soak into the wood’s fibers and react with air to form a protective finish.

 

Seaton Hall’s Most Popular Finishes:

On-the-surface: Minwax Polycrylic, oil-based Polyurethane, Lacquer, Wipe-on Polyurethane In-the-surface: Thompson’s Water Seal, Boiled Linseed Oil, Tung Oil, Danish Oil

Each product has different advantages- resistance, durability, ease of application, just to name a few. There is no one answer for the best finish. Instead, the designer must have a brief understanding of each product and select the best finish for each application.

Resistance- A protective finish can preserve the integrity of the wood- both in resistance to heat and spills. Varnishes contain a blend of alkyd, phenolic and urethane resins. Once cured, varnishes provide the most resistant finish. On-the-surface products will turn from clear to milky or cloudy as they react to heat or chemicals.

 

Durability- In high use areas, finishes must be able withstand abuse. For example, wood flooring receives much more traffic than cabinet doors. Typically, wood flooring is finished with oil-based polyurethane. It may not be the most durable, but it’s lifespan can be as long as ten years before refinishing is necessary. Some may choose to finish flooring with a polyx-oil which has a shorter lifespan, but is easier to repair small portions. Lacquers, depending on the blend, offer a good balance of durability characteristics.

 

Ease of application- This point of comparison is relative. A hobbyist woodworker is capable of applying all of the finishes discussed, but some are easier than others. Penetrating oils simply need to be rubbed into the surface in excess, then removed with a clean cloth. Polyurethanes and lacquers can be applied by brush or roller, but for the best consistency, they should be sprayed with an expensive paint spraying system.

 

In design+make, we struggled choosing the best finish for our wood products. We ended up settling on several finishes, each suited to the piece’s use. Our wood tabletops will receive moderate use so durability was our main priority. On-the-surface products will form a thin film on the surface that has enough elasticity to expand and contract with the substrate- a very beneficial attribute when working with low grade hardwood. While a lacquer would have provided greater depth and beauty to the wood, we settled on a water-based polyurethane. One advantage to this finish is that the acrylic resins prevent the finish from yellowing as years pass. The first two coats were applied by brush, with a light sanding between, with a final coat applied with a high pressure low volume spray gun.

 

Other wood surfaces, like our cabinetry received different finishes. The cabinet drawers received two coats of a traditional wipe-on polyurethane. This product is extremely easy to apply, dries quickly, and allowed us to streamline the building process. The drawer slides will never see direct human interaction, but to preserve the functionality of the wood, the maple was coated in a carnauba wax finish.

 

It is one thing to create a beautiful product, but if the finish doesn’t meet its’ anticipated future use, is it still a good thing? While we made a sacrifice not to use a lacquer which would have looked better on day one, after five years of exposure to the elements, our water-based acrylic blend polyurethane will look as good as the day it was applied. The satin finish shows the characteristics of the pallet wood, just another little advancement in our design intent. As designers, we don’t need to know everything, but we should at least know a little bit about everything. From there, we can use our resources to make the best choice for each application.

Written by Max Taylor