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Sad News About a Good Product

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There is an old joke about the man who drank a quart of Varnish. He had a terrible end but a beautiful finish. That's sort of the story about varnish today. The old fashion varnish is on its way out, which is sad because it has is such a wonderful product.

Traditional varnish (sometimes called Spar Varnish) is a resin in an oil base with solvents. It has natural UV protecting properties. It is semi-thick, tends to flow off brushes nicely, imparts a warm amber color to surfaces, and is easy to re-apply over old varnish providing that the old varnish is not too badly degraded. It also sands nicely and, I think, smells good.

It is common on wood trim on boats and a common 'trick' is to apply over an epoxy coated surface. That surface might be the epoxy covered hull of a newly built boat, or an epoxy resin coated piece of wood trim from the cockpit of a larger boat. The varnish protects the epoxy from UV damage and the epoxy gives the varnish a nice and stable surface to bond to. The resulting epoxy/varnish coating system is much more longer lasting than either one alone.

Some professionals add extra solvent the the first few coats of varnish they are applying over wood. This makes the varnish thinner and helps it soak into the wood better, thus giving (in theory) better adhesion for the entire system of multiple coats of varnish (some folks will apply 8-12 coats of varnish rather than a simple 2 or 3). Note that is may be a violation of local VOC restriction laws.

Another professional 'trick' with varnish is to apply it to all uncoated wood surfaces that are to receive a coat of paint. This way if in the future one wants to give that wood surface a clear coating that shows the wood pattern (i.e. a varnish or clear poly finish) the varnish first coat will have prevented the paint's pigments from penetrating into the wood, making sanding away all the pigmented paint much easier.

The problem with traditional varnish is that it contains lots of solvent, more than air quality, VOC regulations (VOCs are the solvents in products) allow (see www.epoxyproducts.com/voc.html). This is why traditional varnish is often difficult or impossible to purchase now. Fortunately all states except California have a quart exemption rule. This means you can purchase quart units of traditional varnish, but not gallon units. California has done away with the quart exemption rule. Other states are considering it.

Some varnish makers may not want to bother with 'only quart cans.' I think some varnish manufacturer (especially outside the USA) may not know the legal rules and I also think that many boat supply stores/hardware shops pretend not to know. Some states allow for the sell of existing old stock.

Let the buyer beware....

The words 'varnish' or 'spar' don't seem to mean much of anything and their use is not a guaranty that the product is real, traditional varnish. I have seen products called urethane varnish, spar urethane or simply spar varnish, or simply varnish that is not the traditional varnish product. These new products usually were developed to replace 'real' varnish with a product that as acceptable levels of VOC. With all the ones I have examined they look, smell, apply nothing like real varnish, and in the few tests I have done, did not perform as well (they also tend to be thinner so it takes more coats of them to equal a single coat of real varnish). You have to read the label carefully to see what you are getting. If 'water' and/or 'urethane' appear on the label, it is not traditional varnish.

These new products may, or may become, superior to traditional varnish. I don't like them at this point in time, but that is personal opinion. You will need to test them yourself to your criteria. In the meanwhile, I will stick to traditional varnish.

Because real varnish is getting hard or impossible to find, we do sell it along with our epoxies. It is our own private label varnish. We take advantage of the quart packing exemption (in all states but California) in order to sell it. Thus, you can only purchase it in quart cans. This product can be found in our marine catalog at: www.epoxyproducts.com/5_urethane.html (it is not a urethane, but all the none epoxy coatings we have go in this section!), and in our industrial/residential catalog at www.epoxyproducts.com/e_nonepoxy.html section.

Note that this product can only be shipped by ground and cannot be shipped by air or outside the USA. This usually also precludes shipment to Alaska and Hawaii.

Copper powder can be added to epoxies (including our ESP 155™ epoxy sealer), our traditional India Spar Varnish™, our clear water-based Water Prime™ epoxy, and our water-based acrylic sealer Bio Vee Gloss™ as a decorative pigment. Copper powder can be found in our Marine Catalog as well as in our Industrial/home Catalog.

Chemistry of Varnish

Let's start off by talking about what goes into manufacturing traditional, ‘oil based' (solvent based varnish).

1) resin
2) oil
3) drying agent
4) solvent
5) possible proprietary additives

RESIN: Phenolic resin is considered to be the best, followed by alkyd resin which is more common. However, in checking out the so called top varnishes, they seem to be a blend of phenol and alkyd. There are also polyurethane resin varnishes, and there are real similarities between solvent based polyurthanes and traditional varnishes.

OIL: Generally either tung oil or linseed oil. Tung oil is considered better and it probably is but some of the ‘better' is perhaps marketing hype. Usually varnish containing tung oil make it very clear on the label. When used by itself (not in a varnish product) on wood tung oil is superior to linseed oil. It is not often possible to tell what oil is used even when viewing the MSDS (material data safety sheet) because unlike the resin and solvent, it is not considered hazardous and need not be listed. It appears that the best vanishes use tung or a tung oil / linseed oil blend. How much better this is than a pure linseed oil is unknown and other factors probably have more influence than the simple tung oil vs. linseed oil debate. Linseed oil reportedly yellow, darkens, ambers more than tung oil.

One of those other factors is the ratio of resin to oil. The formulations that use more oil with the resin are called "long chain varnishes'. Spar varnish differs from ‘regular' varnish by using more oil. The increased amount of oil in the varnish add more flex to the product, needed outdoors when temperatures and moisture levels vary so much. Varnish for interior furniture would use less oil and be harder and more brittle varnish than spar varnish. I suspect that different manufacturers have different resin oil ratios and that the selection of what resin(s) and which oil(s) also impact the resin oil ratio.

DRYING AGENT: These are small amounts of metallic compounds that get the varnish (and other similar coatings) to cure. There are probably several options (which drying agent(s) and amount of drying agent) that the manufactures have to control the dry time of the varnish. You will not find much information on the drying agents used in your varnish.

SOLVENT: The most common solvent for varnish is mineral spirits (sometimes called stoddard solvent), but I have seen other solvents used/listed on ‘high end' varnish. Note that the solvent's rate of evaporation varies with the solvent so the cure time of a varnish is based upon the drying agent and the solvent type and amount.

Most damaging to the sale of varnish is the various groups around the country that regulate air quality by controlling the amounts of solvents in paints and coatings. Varnish unfortunately takes/requires a lot of solvent. Around 50% of varnish is solvent, well above the acceptable solvent levels in all US locations. Fortunately all states but California have what is called the "quart exemption". This allows the sale of high solvent coatings if sold in quart units.

PROPRIETARY ADDITIVES: We can assume that vanish manufactures add things to their varnish to improve certain properties that they want to modify. UV absorbers or blockers immediately come to mind. Perhaps (a guess) something to make linseed oil act more like the more expensive tung oil. Additives that also control cure time and viscosity might also be used.

VARNISH ALTERNATIVES: The term varnish is generic. Lots of coatings etc. are called varnishes for all sorts of professional and marketing reasons.

There are water based coating that may be called water based varnish or water based polyurethanes. Most professions seem to find them not up to the quality and performance of solvent based coatings for exterior use.

There are solvent based 1 part polyurethanes and 2 part polyurethanes (called LPU coatings) that can be clear or tinted and used as varnish alternatives. There is also a class of coatings (including clear) that are called polyaspartic coatings that have increasingly popular. How do these compare to traditional spar varnish?

There is not right or wrong answer. If find the clear LPU coatings to have superior performance but are less user friendly, more expensive, thinner and lack the warmth and thickness of traditional varnish. I have used them over varnish with success.

I am still experimenting and testing the new wave of polyaspartic coatings as a varnish alternative. Currently polyaspartic coatings are used primarily on garage floors.


PERFORMANCE: It is very difficult to rate the performance of different varnish brands against each other. Climate/weather conditions, surface preparation all come into place besides the varnish itself. I suspect that people that use the higher priced varnishes, generally spend more time on surface preparation and ‘following the directions', use a better quality brush, etc. than those the purchase cheaper products.


Our India Spar varnish is a long chain varnish using a phenolic/alkyd resin. The oil used is unknown but assumed to be linseed oil. It is not know if any tung oil is included. The solvent is tractional mineral spirits.

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We do sell traditional spar varnish (industrial/residential site)

Find it in our boating/marine site