# UV protection in a clear finish



## Sark (May 31, 2017)

Looks like an interesting product, I may try it. A water-based marine varnish. The active ingredient is 1-Methyl-2-pyrrolidone from the MSDS, and I don't have any idea of what that is. My guess is that the varnish has acrylic resins but none are listed on the MSDS.

Maybe some of you chemistry buffs could help out here.


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## RichT (Oct 14, 2016)

Good review, thanks for posting. I'll be interested in your followup regarding the color of the wood.

My understanding is that exterior finishes have UV inhibitors in order to protect the finish, not the wood. One that I've been planning to experiment with is OSMO UV Protection Oil to see if it aids in protecting the color of wood.

We'll see.


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## BigMig (Mar 31, 2011)

Thanks for posting…looking forward to your periodic updates on the UV protection.

Thanks Bill!


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## CaptainKlutz (Apr 23, 2014)

Thanks for sharing!!

Chemistry time:

N-Methyl-2-pyrrolidone (NMP) is mostly used as a slow evaporating (low VOC) solvent that is water miscible (mixes easily, does not dissolve). While low VOC, it is still hazardous, and easily absorbed through by body. It has relatively high exposure limit for human body, but needs to be treat like any other dangerous solvent in shop. It has somewhat oily texture when rubbed between fingers compared to water.

Find it in most paint strippers, and adhesive removers (Goo Gone). Is commonly used in citrus based cleaners to allow blending Inorganic non-aqueous solvents (sulfuric acid, ammonia, etc) with water.

Also has rare ability to cross link with sulfur based compounds, one example being used to remove hydrogen sulfide (rotten egg smelling gas) from petroleum products refining. It is also one of few solvents that can dissolve cross linked poly-amide, poly-imiide, poly-sulfide, and silicone polymers; and has been used to create solvent dispersion of these polymers. Which is part of reason it works well as adhesive remover.

If I were to SWAG the Total Boat Varnish products chemistry; would have to assume they have dissolved cross linked natural resins, shellac, (both typical varnish components and safe for humans) and maybe a short chain poly-amide resin into a water/NMP solvent blend; with purpose of creating a more environmentally friendly marine varnish? But then what do I know? #IAMAKLUTZ not an expert.

UV stabilizers are nothing more than additives. UV stabilizers are classed in two types; Ultraviolet Light Absorbers, (UVA), and Hindered Amine Light Stabilizers (HALS). These are typically powders, many add slight yellow tint to compounds, that can be counteracted with blue dyes. Liquid versions exist typically in a glycol/amine base for use in water/solvent based coatings.

UVA materials attempt to absorb/reflect UV energy, sort of like zinc oxide (a benzoate) used in Sun Block for your outdoor skin protection.

HALS materials scavenge the free radicals from coatings/plastics to slow the oxidation (and yellowing) process. Most outdoor rated plastics/coatings will use combination of the two types to ultimate protection.

The biggest drawback with UV stablizers is tendency to yellow as they age. Which makes formulating a perfectly clear finish that also provides good UV protection very challenging.

IME - Marine environment is very harsh towards polymers, and coated surfaces in that market tend to get regular maintenance. So a slight yellowing due extra UV protection is nothing more than a sign it is time to refinish your wooden boat.  
So will be watching your exposure results, watching for any amber tint changes. (wink, wink)

Hope this helps those that care.

Polymers are FUM!


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## BillGo (Oct 8, 2020)

I looked for the OSMO UV Protection Oil, thinking i would include it on the back of my scrap. It looked like I might be able to buy a "sample" size, but I can't find a way to get just a little. I don't want a gallon just for an experiment…. If you know of a way to get a little, let me know and I will finish the back of my scrap with it.


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## RichT (Oct 14, 2016)

> I looked for the OSMO UV Protection Oil, thinking i would include it on the back of my scrap. It looked like I might be able to buy a "sample" size, but I can t find a way to get just a little. I don t want a gallon just for an experiment…. If you know of a way to get a little, let me know and I will finish the back of my scrap with it.
> 
> - BillGo


Woodcraft is starting to carry OSMO. Most of the products are available in 1/8L cans, but I only see the UV oil in 3/4L


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## schugi (Jan 4, 2015)

Thanks for the interesting review. I too am interested in how it holds up.

I've recently been using Epiphanes Clear High Gloss Marine Varnish. I've had test pieces of mahogany and white oak outside year round in the sun exposed to the Minnesota elements for three years and they look as good as they day I put them out there. This stuff levels out great and leaves no brush marks. The down side (why does there always have to be one?) is that it requires about 8 coats (the first ones thinned) to get the full protection. I originally finished my patio table and chairs with Waterlox marine sealer and varnish and that started flaking off after a couple of months. I sanded it all the way back down and gave it the Epiphanes treatment (only took me 9 months) and so far so good!


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## BillGo (Oct 8, 2020)

One month in… This wood has been out in my sunroom, in direct sunlight, getting turned every morning.









This is the unfinished side. You can see the stripe down the middle where the painters tape was wrapped.









This is the finished side. You can see the Halcyon on the right has a redder color. It does seem a little redder in the picture. It is harder to see much of a difference between the polyurethane and the Halcyon. I wish I had done this a little differently now. I wish I had wrapped the tape around the finished sections of the wood.


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