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Anyone know anything about this new to me GF UV Cure Urethane? The info. given is pretty minimal with no description of what type of UV-B light source is needed. Sounds pretty interesting for really tough applications though.
John
[url=https://generalfinishes.com/professional-products/water-based-topcoats-and-sanding-sealers/uv-cure-urethane#.WToCP8a1vIU][/url]
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That is interesting. Seems like they would provide a little more info about the curing process. I'll have to keep that product on my radar.
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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Does GF answer phone calls these days?
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John, I've tried a few UV cure products but I didn't know GF was making one now. The ones I used were finishes and urethane type repair patches like you would use for a boat or body repair. We had a hand held UV source we used but based on what the rep told me you can just put it in the sun and it works just as well. I think the best option would be a hand held source though. I'm not sure how much the one we used cost but I can check. I have been working on a finishing class with either PPG or ML Campbell. If I can get it put together I will let you know. The PPG class would be in Baltimore but the ML Campbell class would be a few hours north of me so much closer to you.
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Thanks for the input Dave. Baltimore's not that far and I've never really been there, so I might be up for a trip.
John
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They seem to leave that information out.
This company only gives a little more information. They say that the light source needs to be 1" from the surface for curing.
https://proguardcoatings.com/product-cat...-coatings/
It is a common misconception (I believe intentionally fostered by the manufacturers) that "UV topcoat" means that that finish is UV resistant. That is not the case. It only means that it is UV cured.
I used to sell to the plastic pail industry (5 gallon pails). They switched from heat cured to UV cured inks for the exterior of the pails. That created a problem. The pail handle would cast a shadow and the ink behind the handle would remain wet and smear. They had to re-engineer the print line to hold the handle above the printed area to prevent that.
The UV light sources are not cheap: https://www.cureuv.com/?keyword=cure%20u...DQods60E-Q
Also note that the only advantage UV cured finishes have over convention finishes is the speed in which they cure.
From my experience the UV cured finishes are good for vertical surfaces, but the table tops I was contracted to refinish for my local Starbucks did not hold up nearly as well as my oil based brush on finish. The factory finish lasted less than one year and my finish lasted 10 years and looked fine when they retired them.
They recently remodeled that same store and the tables finish is failing again.
For a factory that needs to push products out fast the UV cure is essential. For the rest of us it is not usually essential and may very well be inferior.
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I think Cooler is right. If it offered protection against UV degradation the makers would surely say so. Also, "UV protection" is inavariably about the protection of the finish itself rather than protection of the underlying wood against colour change. The former is pretty irrelevant for furniture and other internal woodwork and is generally aimed at things like boats and other external woodwork where a clear finish is required. A few years ago I carried out a controlled experiment on a number of samples of various wood species and fiinishes which demonstrated that none offered any significant protection against colour change. I have since discussed this with a chemistry professor friend who has done a lot of work in this areaa. He confirmed that while protection against colour change might be regarded as the holy grail by furniture makers, it is unlikely to be found because the amount of UV absorbent chemical required is so great that it would itself obscure the wood, rather defeating the object of the exercise.
Jim
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Well, yes, Cooler is right; this product cures by UV light, it's not a product that protects against UV damage or color change. That wasn't the question, but now that you bring it up, there are indeed several products out there that offer significant UV protection. Epifanes Marine Varnish is an excellent example of one for outdoor furniture, doors, and marine work. It will outlast lesser spar varnishes by a factor of 5 or more. There are several interior rated products as well, GF's HP Poly and SW's KemAqua Plus are two I'm familiar with, and they do work. I used HP Poly on a cherry jewelry box about 6 years ago. The outside color is still no different than the inside. The best products with UV packages use two components, one (often a tin compound) provides protection against the finish yellowing, the other (a hindered amine if that means anything to you) against the underlying wood from aging. Despite what your professor friend may believe, they work and provide years of protection.
John
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(06-17-2017, 08:31 PM)jteneyck Wrote: Well, yes, Cooler is right; this product cures by UV light, it's not a product that protects against UV damage or color change. That wasn't the question, but now that you bring it up, there are indeed several products out there that offer significant UV protection. Epifanes Marine Varnish is an excellent example of one for outdoor furniture, doors, and marine work. It will outlast lesser spar varnishes by a factor of 5 or more. There are several interior rated products as well, GF's HP Poly and SW's KemAqua Plus are two I'm familiar with, and they do work. I used HP Poly on a cherry jewelry box about 6 years ago. The outside color is still no different than the inside. The best products with UV packages use two components, one (often a tin compound) provides protection against the finish yellowing, the other (a hindered amine if that means anything to you) against the underlying wood from aging. Despite what your professor friend may believe, they work and provide years of protection.
John
John,
That's very interesting. I hadn't heard of hindered amines but looked it up. An obvious question is do they have any effect on the clarity or colour of the finish? I have previosly tried an Osmo product which purported to offer protection aginst UV induced colour change, but it was so opaque in the can that its effect was to very significantly spoil the appearance of the wood. Even relatively low levels of opacity in a finish can have a significant effect on lustre which, for me, makes them unsuitable for furniture.
Jim
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Jim, I don't think the clarity is effected, at least not with quality products. Pros wouldn't use them if they did, the SW's product I mentioned being one example. Here's a link to the KemAqua Plus datasheet. Clarity is listed as the second advantage, right after the UV package. Link Blocking UV is not about opacity, although that is how it works with paint, it's about absorption of those wavelengths. The tin compounds used in many exterior finishes like Epifanes absorb only in the UV spectrum and are transparent to visible light. I don't know how the hindered amines work, but I don't believe they affect clarity.
John
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