Varnish

[William Rogers]

I have not seen where varnish is considered as a finish. I have some exotics for small boxes and the like and since most varnish has UV inhibitors it might prolong the color. Is there a reason not to use varnish? I did try some water base varnish and it does raise the grain on the first coat that requires sanding, but not on additional coats. Seemed to work fine.

 

[Doug Freeman]

Interesting you have not seen varnish listed as a finish as I’ve seen it discussed plenty. There are many types of varnish which might be referenced by other terms, the most used probably being “poly” for polyurethane varnish. Non-poly varnish is just about extinct. Some argue “urethane” varnishes are very different from “polyurethane” varnishes, but in my experience and research the end result is indiscernible. A long time ago shellac was referred to as “spirit varnish” and occasionally still is. Waterbased varnish is quite a bit different from solvent or oil based varnish. As wb finishes came into existence mfr called them by the same names as the solvent based finishes there were to replace, poly and lacquer being the most used. This has really confused understanding finishes.

There are 2 general types of varnishes, interior (short or less oil) and exterior (long or more oil). Usually only exterior will have uv inhibitors added. Exterior is more a more flexible but softer finish.

The only issue with exotics relates to adhesion of the finish. The natural oils in some exotics can play havoc with adhesion of finishes. Wiping the surface with dna just before applying the finish is the best attempt to overcome it.

WB finishes have a lot of +’s but a huge negative for me is that none of them create chatoyance, or “cat’s eye” effect. Solvent finishes like varnish, lacquer, and shellac do. I use a lot of wipe on solvent poly on turnings. Steve Sinner has used exterior poly, minwax helmsmsn, on most of his gallery level turnings.

 

[William Rogers]

Thanks Doug, I have seen and use poly urethane a lot, but not spar urethane. I am guessing the two are different to some degree, but not knowledgeable enough on this subject other than application.

I do know that spar urethane is softer than poly, but not the extent. For a lidded box not sure if it makes that much difference.

 

[Doug Freeman]

Agree for a lidded box it doesnt make a difference, and for most turnings it doesnt. Cost may be the biggest differentiator. Exterior varnish can be ~30% more expensive. The uv inhibitors should help hold natural wood color longer but eventually most all turn different shades of brown. How quickly depends on the environment they are in and the finish type and application.

I dont use either for a utensil contact type piece, like a salad bowl. Regardless of the “food safe” debate, hard finishes get scratched all up by utensils. A soft oil finish wiped dry works much better.

 

[Steve Tiedman]

@William Rogers
William, I cannot recommend enough purchasing the book "Understanding Wood Finishing" by Bob Flexner. Originally published in 1994, he did a big update and republished it around 2010. Amazon has an in-depth description of the updated version.

This book is not specific to the needs of any particular worker of wood, rather it informs of the relationship between all the various wood finish products and the wood to which they are applied, and how to use them to give the best results. And Flexner firstly is a man of the trade, a career in wood finishing before educating himself on the science of those finishes and then putting that information on paper in a way that you and I could understand and utilize. One of the best features of the book is Flexner's effort to debunk the myths out there surrounding all the types of finishes. His knowledge is based in science and practice.

I consider this book a tool in my shop, not a book in my library.

 

[Donovan Bailey]

Agree for a lidded box it doesnt make a difference, and for most turnings it doesnt. Cost may be the biggest differentiator. Exterior varnish can be ~30% more expensive. The uv inhibitors should help hold natural wood color longer but eventually most all turn different shades of brown. How quickly depends on the environment they are in and the finish type and application.

I dont use either for a utensil contact type piece, like a salad bowl. Regardless of the “food safe” debate, hard finishes get scratched all up by utensils. A soft oil finish wiped dry works much better.

Doug:
I've picked up a tremendous amount of info from your knowledge on finishes...and I thank you for sharing it with us. I think you could write a book on the subject for us turners.

 

[Richard Coers]

I would never use spar varnish on an indoor project. It's usually formulated to be softer for the extreme wood movement under weather extremes. Varnish just isn't a popular term today, but if you see anything with some kind of resin listed on the MSDS sheet, it could be considered a varnish. Lots of customer perception comes into play when selling finishes in the box store. Things like "tung oil" can be varnish too. Formby's Tung Oil is a highly thinned alkyd resin/soya oil mix that is the same as the old #38 Pratt and Lambert varnish.

 

[Owen Lowe]

As Doug Freeman mentioned above, traditional formulations of varnish are becoming difficult to find but there are still a few commercial products out there. I like Epifanes or Le Tonkinois neither of which are urethanes; I can't stand the smell of urethane varnishes. If you can find phenolic resin varnish, that's my favored varnish type. Behlen's Rock Hard Tabletop Varnish used to be phenoli based but changed 3-5 years ago to urethane.

https://www.epifanes.com/page/clear-finishes
http://www.tarsmell.com/letonkinois_original.html (their balsam turpentine is wonderfully fragrant compared to standard turps)

 

[Roger Wiegand]

I've used Waterlox (a traditional varnish with copra resin) on some turnings as well as a lot of furniture. It's a beautiful finish, quite easy to use. Does take a while to dry and cure.

My understanding was that "spar" varnishes have UV absorbing chemistry incorporated into them. The UV-absorbing molecules are destroyed in the process of protecting the finish, hence the need to re-coat regularly. I've used spar varnish on some box elder pieces to try to prolong the life of the red color-- we'll see how that goes, it's only been a couple years.

I have to admit I've finally been swayed to using some water-based finishes; I've been very impressed with the line from Target Coatings. Their EM2000 product imparts a nice slightly amber tone reminiscent of varnishes, the EM6000 is much like a nitrocellulose lacquer (only much tougher), and the EM8000 conversion varnish sprays beautifully for a very tough, smooth finish. None of them have the horrible plastic look of the consumer-grade water-based clear finishes I've tried in the past. In each case it's easy to pop the grain nicely with a first coat of dewaxed shellac. Terrible experience with rattle cans had led me to avoid spray finishes for decades, I bit the bullet for an organ restoration project last summer, bought a good HVLP gun and have been happily spraying since then. The Target products have completely changed my opinion of water based products.

 

[Adam Cottrill]

Another thing to consider is that varnish or polyurethane may not dry properly on some exotic hardwoods without first applying a coat of shellac. I had this issue once with some boxes with Thuya burl inlays - the boxes dried fine, but the burl remained uncured for weeks. I eventually wiped it off with mineral spirits and sealed it with several coats of shellac. Here is an article on the wood database that discusses this issues in more detail: https://www.wood-database.com/wood-articles/finishing-exotic-tropical-hardwoods/.

Adam

 

[William Rogers]

@William Rogers
William, I cannot recommend enough purchasing the book "Understanding Wood Finishing" by Bob Flexner. Originally published in 1994, he did a big update and republished it around 2010. Amazon has an in-depth description of the updated version.

.

There is a new version of Bob’s book “Understanding Wood Finishing, 3rd Revised Edition:" due out March 2, 2021. I have pre-ordered that book from Amazon. I’m sure it will be a big help.

 

[Doug Freeman]

Doug:
I've picked up a tremendous amount of info from your knowledge on finishes...and I thank you for sharing it with us. I think you could write a book on the subject for us turners.

I appreciate the compliment. A great deal of my knowledge of finishes comes from Flexner and Jeff Jewitt books, and a lot of research, experimentation, and practice over many years on flat and round work. Seems like most ww flat or round, especially newbies, approach finishing as an “oh sh*t” epiphany after they have spent countless hours figuring out how to get to the “ready to finish” point, and then just want “quick and easy”. “Geez, I’ve already spent so much time to get to this point....”

IMO the finish is 1/2 the project, so spend 1/2 your ww time developing the skills.

I also use Target’s line of wb finishes. Possibly the best wb available. Not a lot on turnings - if I want a fully filled “piano” finish, its for an “art” piece that doesnt need abrasion resistance, and I use nc or precat lacquer.

 

[Tom Gall]

Another thing to consider is that varnish or polyurethane may not dry properly on some exotic hardwoods without first applying a coat of shellac. I had this issue once with some boxes with Thuya burl inlays - the boxes dried fine, but the burl remained uncured for weeks. I eventually wiped it off with mineral spirits and sealed it with several coats of shellac. Here is an article on the wood database that discusses this issues in more detail: https://www.wood-database.com/wood-articles/finishing-exotic-tropical-hardwoods/.

Adam

I agree with Adam. I used to use exotic woods almost exclusively as well as some highly figured domestics and burls. I always used a sealer coat (a thin wipe-on coat) of shellac on the exotics - followed by 1 or 2 thin coats of Waterlox (or other topcoat) - but not wiped off. This would produce the same surface finish as 5 or 6 coats (or more) applied in the usual method. This method worked so well I used it for almost all woods. Saved production time too!

 

[Steve Tiedman]

There is a new version of Bob’s book “Understanding Wood Finishing, 3rd Revised Edition:" due out March 2, 2021. I have pre-ordered that book from Amazon. I’m sure it will be a big help.

Hey, I just put in a pre-order for the 3rd edition, too. I didn't see that one previously. Nice.