Very Black Paints

[Jane C]

Hi:

I'm starting to see adverts for a new generation of very black paints based on carbon nanotube technology.  (Before any clever person says anything, yes I have been living under a rock.)

My scope and peripheral tubes do suffer a bit from internal reflections, which are easily picked up when I photograph galaxies. (I won't embarrass the manufacturers by naming names.)

Has anyone had a go with these paints?

If so, what problems did you encounter?

Thanks,

Jane.

[Craney]

I tried a combination of Black 2.0  (undercoat)  and Black 3.0  (top coat)  on the inside of a metallic dewshield.
It wasn't bad, but it did seem to dry with a slight matt grey sheen,  which probably looked worse in bright sunlight than it would at night.

Here are some photos,   start

end

 

I'm not fully convinced.

 

sean.

[ollypenrice]

I do know that there are paints made with pigments and cheaper paints made with dyes. Those made with dyes are not absorbent of all wavelengths, so are reflective just outside the visible spectrum. Heat proof paints for stoves, barbecues, etc., use pigments and are not reflective in this way. This came up as a topic a few years ago regarding the shooting of flat field frames in astrophotography. How relevant this will be in visual observing, I don't know but the blacker (the less reflective) the better has to be true.

My wife is a professional painter and, of course, uses top quality pigment-based paints. The density and intensity of their colour is mesmerizing. I found this fascinating and did a series of macro photos of her palette in use. Make no mistake, there is paint and there is paint.

Olly

[Mr Spock]

This works nicely - Musou Black. Very expensive though. Left tube without, right tube with.

 

 

[Ricochet]

I think the general consensus is that while they are very dark face on they tend to be more reflective at shallower angles and so breaking up a flat surface by giving it a texture will give the best result. There is a thread in the diy section about mixing sand or sawdust into the paint to achieve this. 
 

I used Musou black and flocking on my 72ED in three ways; flocking inside the dewshield, flocking that was then painted inside the OTA, and paint straight onto the inside of the drawtube. The painted flocking gave the best result and the straight paint the worst. The finish when painting it onto a larger smooth surface wasn’t very good either, but on small areas it worked fine. I can still see reflections from very bright objects from areas coated only in the paint, although I think it is still better than the factory paint. 

[ollypenrice]

On 18/11/2023 at 19:42, Ricochet said:

I think the general consensus is that while they are very dark face on they tend to be more reflective at shallower angles and so breaking up a flat surface by giving it a texture will give the best result. There is a thread in the diy section about mixing sand or sawdust into the paint to achieve this. 
 

I used Musou black and flocking on my 72ED in three ways; flocking inside the dewshield, flocking that was then painted inside the OTA, and paint straight onto the inside of the drawtube. The painted flocking gave the best result and the straight paint the worst. The finish when painting it onto a larger smooth surface wasn’t very good either, but on small areas it worked fine. I can still see reflections from very bright objects from areas coated only in the paint, although I think it is still better than the factory paint. 

I don't like the idea of sand escaping near optical surfaces so I'd go for sawdust myself.

Olly

[900SL]

Is there any preformed baffle in flexible sheets that can be cut and bent to shape?

 

[Mandy D]

1 hour ago, 900SL said:

Is there any preformed baffle in flexible sheets that can be cut and bent to shape?

 

I have a large roll of very thin ABS that is covered in dark blue velvet flocking that can be rolled into a 50 mm diameter tube. There is no reason to suppose that it is not available in black.

[doublevodka]

There is this if you are looking for black paint, although not sure if anyone has tested it on a scope yet - https://culturehustle.com/products/black-4-0

I'm one for saving the pennies though so I've been using this stuff to flock scopes https://www.amazon.co.uk/gp/product/B07BGZ82XH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 it's not the blackest thing out there, but it's cheap and a whole lot better than the grey paint used inside most mass-produced scopes

[Astrobits]

Black paints have a matte surface to help reduce reflections. However, at very low angles the light "sees" a much flatter surface than is seen at high angles of incidence. and therefore the surface tends to reflect more of the incoming light than we might have hoped. It's all in the physics of optical reflection at a surface. The only way to reduce these reflections is a physical barrier to the reflected light which is achieved through a variety of ways from adding  a larger particulate ( e.g. sand ) to the paint or putting flocking or baffles on the surface. There is no way to reduce reflections to zero as there will always be small areas at the top of the roughness or baffle that will reflect a small amount of light.

Nigel

 

[Froeng]

On 18/11/2023 at 18:16, Mr Spock said:

This works nicely - Musou Black. Very expensive though. Left tube without, right tube with.

 

 

This is quite impressive! I have had musou black in my Amazon basket for a while and was waiting for a promotion as the (much too big) small bottle is over £30!

I was going to try to apply it on the inside of my C8’s baffle tube, as bright objects have a brightened sky around them…