Archive for June, 2012

Wood Finishing 101 UV Curable Coatings

Thursday, June 28th, 2012

Where do we use these Coatings

UV Curable Coatings:  These are unique coatings in that they cure when exposed to UV lights. They are generally considered a specialty type of coating which requires very specialized equipment. If they are less than 100% solids, then it is necessary to get all the solvent or water out of the product prior to exposure to the curing lights. Once exposed, cure can be completed in a manner of seconds. The end finish usually is very hard and very durable. They may be found in use on kitchen cabinets, doors, millwork, and paneling.

  Up next “Speciality Costings”

Wood Finishing 101 – Conversion Varnishes

Tuesday, June 19th, 2012

Conversion Varnish: These products provide outstanding durability and chemical and water resistance. This is why they have virtually taken over the cabinet industry. As mentioned, they are usually catalyzed with a strong acid catalyst which results in a “worklife”. It is recommended that only the amount that will be used in an eight-hour period be catalyzed. Beyond that, excess material should be disposed of or “decatalyzed”. They usually are quite a bit higher in solids content, 30-45% by weight so often the higher cost per gallon is offset by the need for less material. There are limitations and procedures which must be followed. They are not simple products to use and failure to adhere to the proper procedures can result in severe failures. Some of these precautions include: do not let the material, either catalyzed or uncatalyzed, come into contact with any raw iron or aluminum; the acid catalyst is very strong and should be handled accordingly, catalyst ratio must be followed exactly, and worklife limitations of the product need to be observed.


Up next “Where do we use these UV Curable Coatings”

Wood Finishing 101 – Stains

Thursday, June 14th, 2012

Stains-   Most wood is stained prior to clear coating if it’s not going to be painted. Occasionally there are jobs which have a natural finish (no stain) but for the most part, some sort of stain is applied. The end use and appearance will determine the best type of stain to be used.

Non-Grain Raising (NGR) stain: They are usually dyes dissolved in an alcohol, usually ethyl alcohol. They are spray applied only and very fast drying. In most cases, they will be encountered in the furniture industry or cabinet industry. They are usually used to change the color of the wood prior to application of another, type of stain. For example, on maple, a relatively dense wood that where a very dark color is trying to be achieved, an NGR should be applied to get 60-70% of the desired color. After that application, usually a wipe stain is then applied. This accomplishes a couple of things. First, a dark color can be achieved without threat of inadequate adhesion and second, an often desirable appearance with “depth” is evident. They are not used as a stand-alone stain.

Sap stains and equalizing stains: These are dyes stains, again usually in an alcohol, used on only certain portions of a piece of work, typically only to change the color of isolated areas of the substrate. For example, if you had a greenish streak in a piece of maple or poplar, a reddish sap stain might be applied only to that streak. An equalizing stain on the other hand would be applied to everything but that greenish streak. As above, these are used as only a step in the staining process and another type of stain needs to be applied over these. These stains are usually only seen in the furniture industry. 

Dye stains: These are similar to both of the above but are used as the only stain. A typical application might be for window blind slats. They aren’t the best looking stains but depending upon the application and type of wood, could be acceptable. These types of applications are often dip applied and therefore the solvent blend is usually slower than the above stains.

Spray stains (solvent and water): These are blends of colorants in an appropriate base which is usually fairly quick drying. They allow for a quick staining process (higher volumes). Most millwork and door shops use these types of stains. As their description implies, they must be spray applied.

Wipe stains (solvent and water): These are blends of colorants in an appropriate stain base which provides a relatively long “open” time in order to allow for wiping of the stain. They are usually spray applied with a very wet coat. The time allowed before wiping (open time) can vary from just a few seconds to several minutes. They should be allowed to dry completely before applying a seal coat. Most cabinet and furniture manufacturers use these types of stains as they enhance grain definition and provide more “warmth and character” than spray-only stains.

Stain concentrates: These are typically solvent based only. They are mostly straight tint pastes along with a varying amount of stain base (not reducer). The end user will reduce with an appropriate stain reducer (spray type or wiping type) to achieve a desired color strength.

UV stains: These are stains which are used for applications beneath UV curable coatings. They are very unique in regard to stain base and colorants. They are usually highly specialized applications. They are often necessary to insure adequate adhesion and performance of the UV curable clear coats.

Up next “Where do we use these Conversion Varnishes?”

Wood Finishing 101

Friday, June 8th, 2012

There are an unlimited number of finishes and systems that can be applied to wood. These cover everything from a simple coat of shellac all the way to multiple step (up to 20-30 steps) furniture finishing. Luckily, in the vast majority of the general finishing industry, it is typically a stain, one or two seal coats and a topcoat.  We will discuss briefly, throughout this series of articles the most common finishes that you can expect to encounter.

         The end use of the product will determine the optimum coating that should be applied.  First of all, there are interior and exterior applications. Each of these have their own set of needs in regard to resistance and durability. For example, a house paint is designed for exposure to the weather and is made to last, hopefully, for several years.  A nitrocellulose lacquer may not last much more than a month if it was used as a house paint. On the flip side, you wouldn’t expect to put a house paint on a kitchen vanity and have it provide the look and appearance that is desired.  For this discussion, we will focus on interior products.

Types of Wood Coatings: 

Stains- NGR’s, sap stains, equalizing stains, dye stains, solvent borne spray stains, solvent borne wiping stains, solvent borne stain concentrates, waterborne spray stains, waterborne wipe stains, UV stains.

Lacquers – By definition, a lacquer is a coating which forms a film as a result of solvent evaporation. These typically have been modified to be precatalyzed nowadays. Lacquer types include: nitrocellulose, acrylic, vinyl, cellulose acetate butyrate (CAB), urethane, and waterborne. Usually, lacquers are a blend of two or more vehicles, i.e. alkyd modified nitrocellulose, acrylic/CAB, etc. Lacquers can be sealers, topcoats or a self-sealing product.

Conversion Varnishes– In the simplest terms, a conversion varnish is an acid catalyzed blend of alkyd and urea resin. However, they are most times modified with other resins to enhance dry times and/or provide better performance. They may be solvent borne or water borne.  They typically provide far better resistance properties than lacquers and thusly ALL major kitchen cabinet manufacturers use these at a minimum (some use UV curable coatings).

Paints-These may be pigmented lacquers (or lacquer hybrids) or conversion varnishes. Primers also follow this same premise.

UV Curable- These may be solvent borne, water borne or 100% solids. They may be spray applied, DRC (direct roll coat), vacuum coated or fancoated. These include stains, sealers, topcoats, fillers, and paint.

Specialty Types- Glazes (wipe and breakaway), crackle lacquer, fillers, and toners.

Up next “Where do we use Stains?”


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