Water-Based Polyurethane, Stains, and Other Finishes

Polyurethane finishes use polyurethane resin as a binder. However, because this particular resin is expensive, its often mixed with other synthetic binders such as acrylic resins. In most cases, polyurethane finishes are clear (some have stains or solid pigments added) and they work well at protecting wood surfaces.

However, you should be aware that there are both oil- and water-based polyurethane clear finishes. Of the two, the oil-based types should be avoided. This is because their solvents are very strong-smelling and potentially harmful when the finish is being applied and while it’s curing. While oil-based polyurethanes are admittedly very durable finishes, some very chemically-sensitive persons have found that, even many months after application—long after they should have been cured—they’re still bothersome.

Fortunately, the relatively new water-based polyurethane finishes can be used instead of the oil-based versions. These products tend to dry quickly and generally have little or no residual odor after less than a week. As a result, many very chemically sensitive individuals find that water-based polyurethane finishes are quite tolerable. Other advantages to using these particular products include the fact that they’re commonly stocked in local stores, and they are lower in cost than many other types of alternative, clear finishes. Their big drawback is their wearablity. Some brands warn that they’re “not for use in heavy traffic areas.” Therefore, before purchasing any water-based polyurethane product, read labels carefully to know what you’re getting before you apply it. You should also consider what sheen (light reflectablity) you want. Most brands are made with either a satin or gloss finish, and some have other sheens available.

Acrylic Finishes and Sealants

Clear acrylic finishes create a hard, durable, low- odor coating primarily on woods. Yet, when they’re wet and during their drying period, some formulations are somewhat more odorous than the water-based polyurethane finishes. This is true despite their being water-based products. Chemically sensitive individuals often report that some clear acrylic finishes take up to two months before they are tolerable to them. After that, they often become nearly odorless.

(Note: Many sensitive people find that such sealers help, but not enough to make a bothersome material tolerable. In other words, sealants tend to be imperfect.)

Shellac and Shellac Sealants

Shellac is an ancient finish, being first developed in the Far East. It uses purified lac resin (a secretion deposited on tree branches by female lac insects) as its binding agent. Lac—and therefore, shellac—varies in color from pale, translucent yellow to dark orange, depending on the variety of tree the lac insects live on. As it turns out, shellac produces a f...