Is There Such a Thing as Water Based Varnish?
Varnish – it’s word that has seen a lot of mileage over the centuries. It is perhaps the oldest type of coating chemistry man has kept in his artisan quiver of tools to protect a wide array of objects and surfaces.
Varnish, a resinous film former, was, and continues to be, made from various types of plant-based oils.
With a few exceptions, varnish was always made from tung or linseed oil – with castor and safflower oil showing up later on the scene.
These oils are mixed with metals and different types of spirit oils to help the resin level and dry. Often used by artists to make paints — the alchemy of blending natural compounds grew into what is now industrial paint and coatings chemistry.
It has been a long road to get to a water-based varnish.
When I started formulating in the water medium, the term “varnish” was used in the cabinet and furniture industry to specify a level of durability and visual effect.
We all know that each industry has its specific terminology to help explain products and how they function in the design and production process.
It is a simple list of products to choose from. You have…
Conversion varnish for cabinet and furniture applications…
Spar varnish for exterior marine and architectural use…
Floor-grade varnish (usually urethane) for residential and commercial use…
And, over-print varnish is commonly used in the printing industry.
Today, we see quite a few systems tagged as “water based varnish” or “emulsion varnish.”
The key is to find the right type of varnish for the specific application, and to match as close as possible the performance level of the solvent versions with the new (now, not so new..) waterborne formulas.
So, if varnish is historically oil-based, how can there be a water based, or to use a term I applied to the development of waterborne oils, “hybrids?”
Below are my qualifiers. Some folks may argue my points, but that’s why we are here, yes?
- Oil and water, by nature, do not mix. However, using some pretty cool chemistry, we can neutralize the oil resin and add water-soluble solvents…which remain in suspension! We are now on-track to become water based.
2a. Look at the solvents in the Safety Data Sheet. Certain emulsifiers are used to ‘mix’ the oil and water. These organic solvents are N-Methyl-2-Pyrrolidone (NMP), which has a bit of a toxicity issue with respect to long-term exposure to humans.
2b. DMM solvent is a modern replacement for NMP. DMM – Dipropylene Dimethyl Ether, is a safer cosolvent in terms of long-term exposure. DMM is on the “P” (propylene) side of the glycol series arrangement, and is far less toxic than the “E” (ethylene) series glycols. Ethylene glycols have an established track record of being toxic on both the short- and long-term exposure scale, and contribute to low level ozone, i.e. smog. You and your neighbors will breathe easier when P series solvents are used in the mix.
- Most water based varnish formulators will not tell you what natural oil is being used in their products – probably since they don’t think it’s important to tell you. In most cases of waterborne alkyd resin varnish they call it, “oxidized oil.” This basically means, “we are not telling you,” but the resin is based on tung, linseed, or castor oil. A good hybrid varnish has a blend of oxidized oil and a secondary acrylic blended together. Our Emtech EM8000cv is a prime example.
- Look for resin color as the film ages. If the product is being billed as an oil/water hybrid, or alkyd emulsion, then you will more then likely see a traditional straw/amber color shift in the film formation as it cures. There are a few waterborne hybrids based on tung and castor resins and they tend to color-shift less than the linseed based versions.
- The best part about water based varnish hybrids is that they are very user-friendly. When properly formulated, these blends can offer excellent brush-applied finishes and are wonderful when spray-applied. Using a hybrid varnish will keep your VOC emissions in check and they are not flammable – your insurance company and local fire official will be thrilled!
Most importantly, a well-engineered water based varnish will offer excellent durability, luster and a look/feel that matches-up with old world varnishes in restoration or new construction applications.
What are your experiences with or questions about water based varnish? Please share your thoughts or read what others are saying in the comments section below.
Off topic but I’ll ask anyway: I sometimes used an aerosol can charged with traditional lacquer (like Deft) to touch up a finish. There’s no need to set up spray equipment, the volume of finish needed is small, so it worked and was convenient. Do you think any of your finishes could be sprayed from an aerosol can and would the burn-in that is possible with something like EM6000 still occur so that the sprayed touch-up would combine with the film that was already laid down? This would be a good thing, if possible.
Ed – Thank you for your inquiry. We have looked into putting our water-based lacquers into an aerosol unit and we found that the spray caps are not designed for our types of formulas. However, we do look around for a successful “rattle can” option from time to time.
-JW-
This was a fabulous article nd I appreciate it. I love learning about products I intend to use or do use. If you would please an article about lacquer would be great I’ve been using the EM6000 and I really like it.
Thanks.
Greg – Thank you! Yes, I will be writing a piece on waterborne lacquers, soon.
-JW-
I finally tried your EM2000 for the first time. You guys nailed it. I wanted to know how well it can be brushed, so I hand applied it to a maple and walnut chessboard with a tiger maple frame. It’s just EM2000, no dye, no stain. First, the EM2000 reacted with the grain just like a traditional oil would, darkening and highlighting the figure. Second, it added just a little bit of amber, which I wanted, even with the undyed maple. When I brushed it on, my first though was, “Oh, no.” But, it tightened up as it dried and gave a uniform coating. It pretty much looks like it was sprayed. This all worked in a 65F shop. After 3 hours, I can scuff with 320 or 600 and get white powder. Great stuff. I’m looking forward to using it more. A couple questions:
1. Do coats burn into each other? If I have to level a surface with abrasive, is there enough burn in to reduce or eliminate the risk of ghosting?
2. Is the amber “cooked in” and what I see is what I’ll get, or will the amber deepen over time?
Ed – Thank you for sharing your EM2000wvx experience with us! Yes, the EM2000 will burn-into itself within a 100 hour recoat window. After 100+ hours the adhesion properties will still be very good but the resins will begin to develop a resistance to the solvents in the formulation. I suggest lightly wiping the cured varnish with a water/alcohol mixed of 1:1 to soften the film, then scuff sand with 400 or 600-grit paper. You do not need to use a course/heavy grit schedule Less is more in this case.
Regarding the amber tone of the cured varnish – this is created by the alkyd resin oxidizing over time. It is not a dye or pigment, but an actual color change created by the exposure to oxygen.
Thank you for your continued interest and support!
-JW-