Clear Coating Reflective Glass Beads

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Chris Doe
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Joined: Wed Jul 02, 2014 4:33 pm

Clear Coating Reflective Glass Beads

Post by Chris Doe » Wed Jul 02, 2014 4:47 pm

Hi,

Need some advise from the painting experts.

I'm making some items around my home reflective for better night time visibility -- mailbox, driveway stakes, etc.

I want the items to match my house color, so I've opted not to use pre-made reflective decals.

So far, I've primed and painted the items, and I've sifted on reflective glass beads (fine powder, 1.9 intensity). The retro reflectivity is really great, but I'd like to apply a clear coat to preserve the finish during harsh winters.

From the research I've done, this should be possible as long as the clear coat is rated "water white" (optically clear; 100% acrylic resins). Also, the higher the gloss, the better the optical clarity, which suggests using a paint on, solvent based product.

I've created some test samples and experimented with two pro-grade exterior clear coats, Frog Juice 7000 Sunscreen Gloss and Rolco Acrylic Topcoat Gloss.

Both products look really glossy while still wet and the reflective finish shines through. However, once dry, they become cloudy and seriously retard the reflective finish.

I'm not sure if this is due to viscosity, solvent pop, humidity, or other factors. As per the manufacturers' instructions, both were painted on using a natural bristle brush in thin applications, and the test samples had fully cured before being clear coated.

Any suggestions, please?

Thanks!
Last edited by Chris Doe on Mon Jul 14, 2014 3:21 pm, edited 1 time in total.

erik winkler
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Re: Clear Coating Reflective Glass Beads

Post by erik winkler » Sun Jul 06, 2014 12:04 pm

Both products would do the trick.
But if you brush over the fine powder you applied, you include thousand of tiny airbubbles into the clearcoat.
These will give you the cloudy look.
Solution:
1. Spraypaint it on.
2. After applying use a blowtorch (fire, be carefull with the solvents, because it will catch fire if not done carefull enough) and remove all aurbubbles while clearcoat is still wet.
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
www.schitterend.eu
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Chris Doe
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Joined: Wed Jul 02, 2014 4:33 pm

Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Mon Jul 07, 2014 9:40 am

Thanks for the info, Erik.

Unfortunately, I don't have a HVLP spray gun. I tried the aerosol version of the SuperFrog product last year, and it seemed to introduce more air bubbles than the paint on version.

Last night, I experimented thinning the Frog Juice with 10% mineral spirits for greater flow and to slow the dry time. I also used a foam brush this time to see if it makes a difference with the air bubbles, but I haven't had a chance yet to see how it turned out.

You mentioned that heat could also be used to get rid of the air bubbles. Should the heat source be applied until the clear coat is completely dry?

erik winkler
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Re: Clear Coating Reflective Glass Beads

Post by erik winkler » Mon Jul 07, 2014 10:43 am

Chris,

Take a look at this Video and you will see what I mean.
Good luck.
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
www.schitterend.eu
www.facebook.com/Schitterend.eu

Chris Doe
Posts: 8
Joined: Wed Jul 02, 2014 4:33 pm

Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Tue Jul 08, 2014 9:54 am

Thanks, Erik, for the instructional video.

Regarding my last sample using thinned Frog Juice, it definitely turned out better than using the product right out of the can, but it is still not as retro reflective as my uncoated sample.

Side by side, the coated and uncoated samples shimmer equally as well in direct sunlight, but in low light conditions, only the uncoated sample reflects.

I've prepped some new glass bead samples this morning. Once the paint dries, I'll test using a blowtorch when I apply the coating.

Tyler Tim
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Re: Clear Coating Reflective Glass Beads

Post by Tyler Tim » Tue Jul 08, 2014 3:45 pm

Just an idea... try dusting your clear coat with some glass beads as well.
Sure I paint thing for my amusement and then offer them for sale. A brushslinger could whither en die from lack of creativity in this plastic town my horse threw a shoe in. :shock:

Chris Doe
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Joined: Wed Jul 02, 2014 4:33 pm

Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Tue Jul 08, 2014 4:53 pm

Thanks for the suggestion, Tyler.

Didn't mention it before, but one of my test samples had a base coat of paint only. I wanted to see if the beads would adhere better to wet paint or to wet clear coat.

Unfortunately with the brush on version of Frog Juice, even after thinning 10% with mineral spirits, the end result of dusting was a smalt effect with zero reflectivity.

Maybe the aerosol version will produce better results since it can go down in thinner applications, or perhaps I should thin the brush on Frog Juice with 25% mineral spirits (milk like consistency) as is recommended for spray on applications.

I'll try your suggestion and will post back.
Last edited by Chris Doe on Mon Jul 14, 2014 3:16 pm, edited 1 time in total.

Chris Doe
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Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Mon Jul 14, 2014 3:16 pm

Finally had a chance over the weekend to get back to this project. Here are the results.


Control 1: white paint only
- no reflectivity

Control 2: 1.9 beads only
- best reflectivity, but blackout in wet conditions (loss of reflectivity)

Sample 1: Thinned Frog Juice brush on (3:1 ratio to mineral spirits) + blowtorch over 1.9 beads
- performed slightly better than previous attempt with brush on method (9:1 ratio, no heat), but uneven reflectivity in low light

Sample 2: Frog Juice aerosol + blowtorch over 1.9 beads
- performed slightly worse than Control 2 in low light, but had the benefit of improved adhesion

Sample 3: Frog Juice aerosol + blowtorch (2 coats, 30 minutes apart) over 1.9 beads
- performed slightly worse than Sample 2, but had the benefit of being hydrophobic

Sample 4: Frog Juice aerosol + 1.9 beads over dry paint
- performed worse than Sample 1; beads did not adhere well using Frog Juice as bonding agent

Sample 5: Frog Juice aerosol + 1.9 beads over 1.9 beads
- performed worse than Sample 4; top layer of beads reduced reflectivity of bottom layer of beads


A few things to note:

- The base coat for all of the samples was a high gloss enamel (Rustoleum pro-grade aerosol). I applied three thin coats several minutes apart, and then sprayed on a slightly heavier top coat. While still wet, for all but Sample 4, I sifted on the beads and let it dry completely before knocking off the excess beads and buffing with a stiff nylon brush. If the top coat is too thick, the bead powder will sink and clump, and the finish will not be smooth; however, if too thin, it will dry too quickly and the beads will not adhere uniformly.

- To apply the beads, I used a glass mason jar with a 2" hole cut in the lid and covered on the inside with several layers of fiberglass window screening oriented randomly. The screening broke up any clumps and made for a slow, consistent pour.

- The bead coating will give a bright white base coat a slightly grayish tint when not viewed in direct light.

- I applied the clear coat in my workshop but used the blowtorch outdoors since the Frog Juice label said its vapors are extremely explosive. Working outdoors also had the benefit of monitoring the reflectivity of the test sample during the heating process. I applied the heat immediately (since the Frog Juice product is quick drying) and until the wetness of the clear coat had dissipated.

- I used a mini butane torch rather than a full-sized propane torch since I couldn't keep the propane lit with the constant movement. Both emit CO2 which, what I've read, is what pops the air bubbles. I believe the lightweight nature of the mini torch also allowed for greater precision.

- When used over glass beads, Frog Juice will cure to an eggshell/semi-gloss sheen (as compared to the overspray on my work surface which was very glossy).


To test the reflectivity, I placed the samples 30 ft. away in a heavily wooded area at night time. I then shined a low-powered LED flashlight on the test samples and compared the results to Control 1 and 2. Finally, I misted water on each sample and re-tested. (I performed similar tests in the past with 1.5 intensity beads, but the reflectivity was undetectable beyond 10 or 15 ft.)

Based on my experiments, Sample 3 seems to demonstrate the best technique for clear coating glass beads to achieve a smooth finish and prolonged reflectivity in a variety of weather conditions.

I also learned that aluminized glass beads are now available in powder form. Unlike standard beads, a mirror-like finish is applied to half of each bead to give it a higher intensity. Perhaps this would counteract the effects of a clear coat, although it might have the side effect of turning a bright white base coat dark gray unless intermixed with clear beads.

erik winkler
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Re: Clear Coating Reflective Glass Beads

Post by erik winkler » Tue Jul 15, 2014 3:42 pm

Thank you for posting your results
Realizing we are in the 2nd renaissance of the arts.
Learn, copy and trying to improve...
Still in the learning phase ;-)
Amsterdam Netherlands
www.ferrywinkler.nl
www.schitterend.eu
www.facebook.com/Schitterend.eu

Chris Doe
Posts: 8
Joined: Wed Jul 02, 2014 4:33 pm

Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Wed Jul 16, 2014 8:25 am

You're welcome, Erik.

I ordered a small quantity of the aluminized bead powder and will test it out sometime next week.

Chris Doe
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Joined: Wed Jul 02, 2014 4:33 pm

Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Thu Jul 24, 2014 2:55 pm

Created new control samples using the 1.9 aluminum-coated beads:

(1) All aluminum powder

(2) 32:1 mixture of clear to aluminum powder

(3) 40:1 mixture of clear to aluminum powder


As expected, using all aluminum beads completely masked the white base coat. When shined with light, it is very reflective, but it resembles dark gray primer in normal viewing conditions.

When using a mixture of clear and aluminum beads, the base color is still able to shine through, albeit slightly worse than using all clear beads. The reflectivity for the 40:1 mixture, however, was noticeably better, perhaps because aluminum beads have an omni-angle property which both retro-reflects and scatter-reflects light, whereas clear beads only reflect straight back to the light source.

The 32:1 mixture performed about the same as all clear beads, but it had an unaesthetic pepper-like appearance in normal viewing conditions, similar to some reflective decals which use encapsulated beads rather than prism technology.

Based on these results, a 40:1 mixture appears to be a good balance between translucency and retro-reflectivity. Adding too many aluminized beads, its scatter-reflectivity has a negating effect and the base color is distorted.

I didn't experiment with higher ratios, but any greater, it would probably be difficult to achieve an even distribution of the beads (as it was, with the 40:1 mixture, I had to stop and swirl the jar several times during application to keep the aluminized beads from clumping together).

I haven't tried topcoating the 40:1 mixture, but based on these results, it should outperform the sample with all clear beads. I wish there was a way to get a very smooth, glossy finish like the protective film on decals, but I guess that just isn't possible.

Hope this helps!

Lee Littlewood
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Re: Clear Coating Reflective Glass Beads

Post by Lee Littlewood » Mon Jul 28, 2014 9:17 pm

great work, Chris. The scientific method is slow and tedious, but you get real info at the end.
And of course we get it for free, so what's not to like?

You didn't say if the final mix (40:1 aluminized beads: clear beads; clear topcoat) lets much of your custom base colors show through. It sounds like beads grey out the base color, whatever it may be.

Now could you find a cure for the common cold???
where am i? Now, when i need me...

Chris Doe
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Joined: Wed Jul 02, 2014 4:33 pm

Re: Clear Coating Reflective Glass Beads

Post by Chris Doe » Tue Jul 29, 2014 10:04 am

Thanks, Lee.

The ratio I'll be using is 40 parts clear beads to 1 part aluminum-coated beads (both rated high index, Type 3 -- 1.9 index of refraction; 170-450 mesh), and top coated with two thin applications of sprayed on Frog Juice solvent applied 30 minutes apart and torched immediately for several minutes.

As you inferred, the bead coating will darken any base color and, in my tests, it turned bright white paint to light gray. The clear coat further darkened the color and gave it a slightly amber hue, but it still looks very vivid in the daytime.

As for other base colors, I made some reflective property markers last year using my yellow house paint and all clear beads. The beads were rated at 1.5 and were made of recycled glass (vs the 1.9 beads which use virgin glass). Even with the impurities in the glass, the yellow color still shines through in normal viewing conditions (although slightly darker in appearance than my house) and glows a bright white/yellow in direct light.

If I were to repaint them, I'd lighten the paint to compensate for the darkening effect of the beads and they should be a perfect match.

One other thing I forgot to mention before is that an orange peel effect appears to be desirable when applying the base coat as it promotes good adhesion of the beads. Once dry and the excess beads are buffed away, the surface levels off and has a slightly gritty feel, like ultra-fine wet/dry sandpaper. Although clear coat further smooths things out, there is still some texture, but it is undetectable unless looked at from very close up. And if too many layers of clear coat are applied, the reflectivity is greatly diminished.

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