Varnish what is it

I am a Boatwright early each spring you can find me sanding or applying varnish to brightwork. I like to ask my fellow boat owners what they recommend for a particular job. I rarely get the same answer from two different owners and occassionaly I get a surprising answer.

Varnish is that thin layer of oils thinners resins and drying agents, that protects the ships woodwork from the damaging effects of wind, water and sun. When done correctly the varnished surface will be a mirror high gloss to flat matt finish and usually will warm the color tone of the wood. The main ingredient of the varnish I use is Tung oil. Most varnish is blended from three ingredients 40 to 65% is oil that will enhance color. 15 to 20% resins enhance the color depth and hardness. Finally, 10 to 15% solvents that enhance flow accelerate dry time aid in penetration and improve hardness. Tung oil also called “China wood oil” has been used for thousands of years in China to seal wood and porous masonry. Because of its preserving properties Tung oil trees were once sought after by the US military for preservation of military hardware. Made by pressing the seed fruit of the Tung tree the oil has a slight golden tint and provides a tough water-resistant finish and is considered a drying oil, like linseed safflower, poppy, and soybean oils. However Tung Oil will not darken with age like linseed oil. Other oils such as linseed or soybean may be added to varnish helping it penetrate deeply and hardening the wood soft tissues increasing durability. Polymerized Tung oil is produced by heating or chemical treatment, that substantially increases the viscosity and film-forming quality of the oil. The resulting oil will range in viscosity from very thin, like WD40, to that of 10-weight motor oil. Suppliers Lee Valley Tools and Formbys add evaporating thinner solvents that enhance flow making their product easier to work with and help improve penetration. Resins may be added derived from a number of sources but the chiefly crude oils they are found in the form of phenolics or phenols and are added to enhance color depth. also important is that phenols are germicidal and have been used as disinfectants. During the early part of last century, they were used to protect against wood rot for telegraph polls and railroad ties. Warning phenols may have estrogenic or endocrine disruptive properties. Read all warning labels and directions before using or removing products that contain phenols. Resins can also be manufactured from bioengineered polymers and these may not possess the toxicity levels of those phenols derived by the petrochemical industry. Weather phenol is derived by extraction from oil or bioengineered polymers, resins provide fast drying times and a hard finish and ultraviolet stabilization. Polyurethane resins are organic compounds composed of carbon and hydrogen and are categorized by two family class groups, Aromatic and Aliphatic. The Aromatic group contains benzene and similar compounds. While exposure to benzene has been shown to have serious health issues, including damage to liver, kidney, heart, brain, and bone marrow. The use of benzene based products should be done only in a well-ventilated area to avoid breathing any benzene vapor. The aliphatic family of compounds may be a safer, healthier choice as they do not contain benzene. In aliphatic compounds, carbon atoms can be joined together in straight chains, branched chains, or rings in which case they are called Alicyclic. Further Aliphatic compounds may be joined by single bonds Alkanes, double bonds Alkenes, or triple bonded alkynes. The physical nature of this cross-link bonding increases the strength and helps to make the material tougher. Solvents are versatile used to clean surfaces and alter the properties of other materials. They enhance self-leveling properties allowing a product to obtain a smooth even finish by extending that products work time. Solvents enhance flow, aid in penetration, extend or accelerate dry time and improve hardness. Anti-skinning agents: A type of solvent extends the work time a product will allow the material to be manipulated longer by the user.


copyright2008 Terry Capp

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