UV Clears

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OLD FORUM POSTS

Posted by Barbara Schilling on October 21, 2002

What UV protectant clears are you using? Any specific Successes or failures?

I just put a coat of One Shot UV Clear on my shop door last summer. It went over several old coats of clear poly. I agressively scuff sanded the poly and tacked it off before putting on the UV Clear. The clear is failing on the bottom 12 inches of the door. It is crackling and popping off. Almost looks like it did not adhere properly. That is also the area where the old poly was in the worst shape. Once again, I am reluctant to use ANY clears. None of them seem to have any durability.

Any suggestions?

Billy Bob

If the problem is on the bottom 12 inches of the door, wouldn't that indicate a moisture issue?

My vote is to NEVER (or extremely rarely) use clears. Especially if you are new to the biz.

Kent Smith

No matter how much sanding is done, acrylics will not stick to polys. Having said that, single component UV clears are made to protect the surface over which they are applied. Their purpose is to extend the life by half-again-as-long. While it will protect itself too, the resin is still subject to UV and will lose its adhesion in a period of time, roughly within 6 to 36 months. This depends on adhesion, UV exposure, moisture, molds and midews, abraision, et al. The only clears suitable for long term exposure are two component and the window for them has shortened in the last 3 years due to environmental issues.

Barbara Schilling

So, Kent,
(I knew you'd have something to offer here) Do you put UV clear on digital (Edge) prints? If they are supposed to be good for 3 years (process color) what good will the UV do if it will lose adhesion in 6-36 months? And to take a step further, Is there EVER a reason to use a UV clear? Only time I used it recently (on a sign) was LAST YEAR to help a customer get "one more year" out of a badly chalking and fading sign that he wanted to replace with Sandblast, but didn't have the cash yet. That was 15 months ago! and it still looks like new. Boo Hoo.

Kent Smith

Well...I find the waterborne UV clear which is an acrylic with inhibitors in it, to be a good way to get a little more mileage out of combinations of vinyl and paint. It acts also as a good overall edge sealer for vinyl. Certainly the properties of the acrylic are such that it does help to protect itself and the pure acrylic adhesion is better than single component poly. I have used it on Edge prints and seem to get better performance. Sometimes I think that the added gloss alone helps to prevent fade and certainly helps prevent abrasion. I have a lighted sign face which faces south at this high altitude which has Edge printed logo that I did 6 years ago. The yellow faded 2 years ago but is not a critical component with the white plastic suitable, the forest green is weak by still there and the black is more transparent but good enough. I think without the clear, it would have been gone in 3. Still, it is difficult to ask a single component clear of any type to perform multiple tasks. When you get good UV protection, you often lose moisture protection. When the adhesion is superior, the resin does not hold enough UV inhibition to be worthy. When you have good moisture barrier, both base adhesion for expansion breakdown and UV are poorer. The two components are better but sometimes they are more subject to expansion/contraction issues. Pigmented coatings of all types have always protected their resins better to retain adhesion. The old root resin spars lasted so well because there were less sophisticated substrates to which they adhered and they were so sticky and elastic that they held well. They also were so amber in color that they protected themselves well. Add to that the quantity of soluable lead in them and they lasted because of black magic alone. We also rarely hear of the metal background wood framed signs with varnish peeling, we only remember the ones that didn't. While clears have their place for applications where no other finish will do, remember that we used to recommend re-clearing fire trucks and window lettering every year or so. (check the first edition of GL Tech.) One of my first jobs when I got my driver's license was to go around to all the fire houses where Dad's lettering was and re-clear each truck, for a small fee of course but regular work.

Barbara Schilling

Thanks Kent, lots of info.

What is the actual name of the waterborne UV acrylic clear you mentioned? I am out of the loop on waterborne paints, since my sojourn into DEKA was less than satisfactory. The UV clear I have been dabbling in is the 1 shot brand. Haven't tried the current "frog juice", although I know a decade ago it was actually Matthews Sunscreen clear.

Topcoating old Fire truck lettering? Ah, those were the days. I used to offer to topcoat older trucks as a "bonus" to secure the order on a new job. The clears were so poor, that jobs would be failing in 12-18 months. And of course the fire fighters never noticed, so by the time I cought them they were already damaged beyond repair. This was partly due to the constant washing they get. I am glad to be protecting Fire truck Gild with tedlar now.

Barb

Kent Smith

The waterborne is Chromatic UV Clear which is Ti-Cote with UV inhibitors added, now owned by 1Shot. Tough stuff which can also be recoated. The frog juice is still the same as I understand it, solvent based modified acrylic (modified with what, Butch is rightfully not saying). While I too use the Tedlar for many applications, still do some hand gilding with GripGuard clear two component with brush/roll hardener. The GripGuard is Sikkens with a sign paint label, hence cheaper, available form the sign distribution network (Midwest has it near you) and the brush/roll hardener is a bonus from the Wyandotte techs. The hardener which 1 Shot now has, works in any resin clear (not acrylics) to give it the added resistance to breakdown but not as good as pigmented alkyds. I have been able to clear over old lettering with good results with the GG clear and have been using it since Bill Riedel put me onto it during hurricane Hugo...another story altogether.

Rick Sacks

Kent, Do you find differences in the brands of two part automotive clears and the different brands of synthetic enamel hardeners?

Kent Smith

Absolutely. The variables are the ratio of solids added which may or may not be compatable with other resins and the ratio of isocianites and methel solvents. The Sikkens products have high solids and can be made brushable as I have indicated. Dupont tends to have less solids and are formulated for spray, multipass build up. PPG also tends to have fewer solids in all their two components which includes the current fomulations of Matthews which used to have a brushable formula. ALL other brands on the market purchase their raw materials from the major manufacturers such as Dow or Dupont. The synthetic enamel hardeners are all pretty much the same since they are based upon Dulux technology. It was an alkyd just the same as lettering and bulletin enamel. The purpose of the enamel hardener is to enhance the cross linking of the resin during the cure process so that all of the resin cures properly. The result is a harder top finish and subsequently better gloss hold out as well as having a more complete paint film.

Rick Sacks

I've phoned all the suppliers in three counties looking for someone that sells the Sikkens products. How do you obtain such items?

Ben W. Collins - Sikkens

To locate a Sikkens dealer in your area, you can go to: www.nam.sikkens.com
or you can call them at 800-833.7288. The website has a scetion on locating a dealer of their products by states.