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Protostar FlockBoard vs Krylon Ultra-Flat black

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#1 FlorinAndrei

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Posted 16 February 2013 - 09:51 PM

Recently I had the opportunity to take a good look at the Protostar FlockBoard light trap, and compare it to the Krylon Ultra-Flat black 1602 spray (some say it provides better light absorption than most black paints).

I used the FlockBoard on a small solid tube dobsonian, the interior being already painted with the 1602 black spray.

The comparison was very easy to make while only half of the FlockBoard was installed, inside the bottom half of the tube. The upper side revealed the existing 1602 coating.

Since the tube's diameter is pretty small (200mm, or 8"), it was hard to apply a uniform layer of 1602 inside. Some spots were a very deep, non-reflective black, even at a very very shallow reflection angle - while other spots were a bit more shiny.

Where the 1602 was non-reflective, it was quite a bit LESS reflective than the FlockBoard. There's no doubt about it. The 1602 reflected essentially no light that I could see, an incredibly dark shade of black. The FlockBoard would shimmer a little bit, with the reflection actually increasing a small amount at a very shallow ("grazing") angle of reflection.

However, where the layer of 1602 was imperfect, the FlockBoard outperforms it. The shinier parts of the 1602 were quite uniformly reflective, whereas the FlockBoard would exhibit very tiny and sparse reflective speckles. All of this, again, seen at a shallow angle.

Overall, considering both the good and the bad spots of the 1602 coating, I would guess the performance was about the same, compared to the FlockBoard.

If the tube diameter was larger, I believe I might have managed to apply a more uniform layer of spray, and then it would have outperformed the FlockBoard overall.

I decided to keep the FlockBoard, since it achieves about the same total reflection, and additionally the layer of light trap provides a small amount of thermal insulation.

I can't say I've observed a marked improvement in telescope performance after installing the FlockBoard over the 1602. The amount of light scatter from Sirius is about the same. The Pup is as hard to see as ever. Jupiter seems to benefit a little. No comparisons yet for the Moon or Sun (with a white light solar filter). The very small improvements I've seen could be attributed to the fact that I've also cleaned the mirror, which was extremely dirty.

If a different flat black paint was used, not as good as the 1602, I think the FlockBoard would outperform it overall. The 1602 is quite visibly better than regular flat black paints.

So, bottom line is - if your painting Kung Fu is very strong :) then just use the ultra-flat black 1602 spray; but check the result and make sure it still looks uniform at a very shallow reflection angle. Otherwise, the FlockBoard is probably a better option, and easier too. The FlockBoard is equivalent to a very good, very uniform layer of flat black paint.

No pictures, sorry. It would have been difficult to capture all those subtle shades of black anyway.

#2 FeynmanFan

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Posted 17 February 2013 - 06:03 PM

Could you find a substrate that could be painted with the Krylon in a flat state, allowing even coverage, then rolled for installation into the tube?

#3 Bob Myler

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Posted 17 February 2013 - 07:22 PM

I thought Krylon Ultra-Flat was not longer available - replaced by its flat black "camo" paint...

#4 careysub

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Posted 17 February 2013 - 10:25 PM

I thought Krylon Ultra-Flat was not longer available - replaced by its flat black "camo" paint...


What actually happened (it turns out) is that they dropped it as a consumer product and shifted it exclusively to industrial supply channels.

It can be obtained from the movie industry supply house "Film Tools":
http://www.filmtools...ulflbl1shb.html

#5 Datapanic

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Posted 18 February 2013 - 12:42 AM

I wonder if there is a difference between 4290 Ultra Flat Camouflage Black and 1602 Ultra Flat Black?

There are a lot of plus and minuses for using paint or flockboard depending on the application. For smaller tubes, I think paint is the way to go - it costs less and is quick and easier to do.

But with larger jobs, such as the Horsetrail Cave tube, I went with Flockboard. With a 4x8 foot area of inside tube, I felt it would have cost a lot more to try to apply primer and then paint and get a good coat all around than it would be to cut up and fit Flockboard.

The upside of Flockboard is that I have an even 'coat' up and down the tube, but the downside was I added 6 more pounds of weight to the OTA which meant another 6+ pounds to counterbalance or 12+ pounds total more on the mount! It only took about 2 hours to fit the tube with the material, painting would have taken a lot more time and would have been a lot more difficult to get a good coat.

I haven't noticed any shiny speckles on the Flockboard I installed, and I use a lint roller to remove any debris that might land on it. I think one benefit of Flockboard is that its texture scatters light better than paint, but I don't know which is better at not reflecting light. One thing for sure, Flockboard is very black.

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#6 careysub

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Posted 18 February 2013 - 02:12 AM

I wonder if there is a difference between 4290 Ultra Flat Camouflage Black and 1602 Ultra Flat Black?
...
I think one benefit of Flockboard is that its texture scatters light better than paint, but I don't know which is better at not reflecting light. One thing for sure, Flockboard is very black.


There is a difference. They are different forumulations, and the 1602 Ultra Flat is blacker.

Regarding 1602 (or any spray paint) vs flockboard - the flockboard is blacker over all.

I tested 7 different flat black spray paints and all of them have one particular angle at which they are surprisingly reflective. This complicates the comparison since the relevance of the reflection depends on the system design. If the reflection angle light just gets trapped again it is of no consequence.

Joanne's Premier Velvet is even darker than the flockboard.

In the 7 paints I tested, the second darkest after the 1602 was the 4290 Ultra Flat Camouflage Black, just edging out the next competitor.

#7 Datapanic

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Posted 18 February 2013 - 02:27 AM

The Joanne's Premier Velvet sounds interesting - but how to get it secured inside larger tubes?

That pic of the Flockboard inside the tube I posted - the original photo was so black that it showed hot spots on my camera that I didn't know I had before.

When using rattle can flat black spray paint inside of scope tubes - I just lay it on thick and not worry about runs or buildup. The end result is a sand-paper like texture which I'm sure helps in light scatter. But, when painting components, such as secondary holders, spiders and even nuts and bolts inside the tube holding down finder rings, focusers, tube weights and so on, a good flat black is very important.

#8 careysub

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Posted 18 February 2013 - 02:45 AM

The Joanne's Premier Velvet sounds interesting - but how to get it secured inside larger tubes?


I would try double-sided carpet tape.

When using rattle can flat black spray paint inside of scope tubes - I just lay it on thick and not worry about runs or buildup. The end result is a sand-paper like texture which I'm sure helps in light scatter. But, when painting components, such as secondary holders, spiders and even nuts and bolts inside the tube holding down finder rings, focusers, tube weights and so on, a good flat black is very important.


Texturing the surface before spray painting is almost always a good idea. Lots of ways to do that.

#9 mconnelley

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Posted 18 February 2013 - 03:55 PM

Hello:

One idea that I have been curious about is to spray a layer of the 'stone finish' paint, then overcoat that with flat black. Home improvement stores often have spray paints that dry with a very rough surface to mimic stone, with stone-like colors. I would expect that rough surface would help to knock down the problem of grazing incidence reflection for black paint. Has anyone tried this experiment? Black velvet is a really amazing light trap, and is what I currently use on my scope.

Cheers
Mike

#10 FlorinAndrei

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Posted 10 March 2013 - 11:58 PM

There are a lot of plus and minuses for using paint or flockboard depending on the application. For smaller tubes, I think paint is the way to go - it costs less and is quick and easier to do.


Perhaps, but not spray. It's hard to apply it correctly when the tube is very narrow (like for a small dob) and as a result it's more reflective than it should. That's one reason I ended up using the FlockBoard instead for the little tube.

I haven't noticed any shiny speckles on the Flockboard I installed, and I use a lint roller to remove any debris that might land on it.


No, it wasn't dust. It was the material itself. It was a very subtle effect. If you could show it to you, you'd go "oh, I see what you mean". But it's impossible to capture it with the camera.

It was the difference between the best spots of 1602 spray, which were absolutely non-reflective at a shallow angle, and the FlockBoard, which was just a tiny bit reflective - and looking closely I could tell it was tiny fibers in the material itself that were catching light at the wrong angle and reflecting it a bit.

It was not a strong reflection. Overall, FlockBoard is very non-reflective. It's definitely a good flocking material.

The bad spots of 1602 were more reflective than the FlockBoard. In a bigger tube, I think I could have done a better job with the spray.






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