Flocking Advice

[Darkplague]

Hi,

Ive just dissassembled my 12" completely, and have bought some felt/velvet to line the whole of the tube with.

However after just reading some posts on cloudy nights, people are advising against this because they say that it will be too insulated and won't cool down effectively. They also say that the felt will act like a sponge and absorb water on really cold, dewy nights.

Anyone have any problems like this with felt or velvet material????

I doubt that it could be as bad as people say it would be but some reassurance would be nice.

Guess Im starting to panic because once this is done, it will be near impossible to remove because I'm using contact cement.


Mark

[ballaratdragons (Ken)]

Mark,

There are a few thread in here somewhere about flocking materials.

Beware of the felt varieties as they give off millions of fine particle which collect on your optical surfaces!!!!! They are also dust traps.

I have heard one person mention how felt products absorb moisture and trap it which can't be good for rust!

If you have the scope dissassembled you might consider painting the inside with Blackboard Paint which is less reflective than ordinary Matt Black paint.

If you can't get hold of any blackboard paint you can make your own by mixing Talcum Powder into ordinary black or Matt black Acrylic paint (which is how they make blackboard paint!).

To get the mixture right (you will need more Talcum Powder than you think) mix the powder in and test some on a scrap peice of something. You will have to let it dry to see the final result. If it is not right, just keep adding Talc until the required result is acheived.

[rmcpb (Rob)]

Yep, the blackboard paint over some of the stone finish paint that gives a rough texture works well.

[asimov (John)]

Iv'e also read an iten where a guy painted the OTA out, quickly sprinkled a layer of fine saw-dust over the wet paint, let it dry, then another coat of black over the top.

[rmcpb (Rob)]

Yep, flat black paint over any rough surface will be better than the dark grey, smooth, semi flat paint used in most tubes. Its a matter of picking your poison, I chose the paint option becausse it seemed to be a bit more controlled than the sand/sawdust option. Both work though.

[mch62 (Mark)]

A little trick if you have one is to use a green laser pointer to see what the reflective properties are like of different surfaces.
You would be surprised at what reflects off velvet and some black board paints.Some black board and matt black paints use either a fine grit and or talcum power type materieals .
These tiny particles reflect and fine haze when using a laser.
The velvet gave a very nice pattern of green.

One idea i found on the web and have tried with the laser but not used on the scope yet is a towl (bath towl, towling) dyed black using ordinary flat black paint.
This seals the towl from moisture and acts as a light trap (thousands of tiny baffles)
Of all the surfaces i have bounced the laser off this has shown the most promiss and would like to use optical black paint instead to soak the towl.

Mark

[Darkplague]

Ive flocked my whole tube with Black Velvet from spotlight.
Wasn't that hard to do but took a lot more time than I was expecting.

Now I'm making a dewshield and I am machining up a set of "bob's knobs" for easier collimation. Pictures will be coming soon!!!

[cristian abarca]

Hi guys

Would using a fine texture then painting it black work? I,m a painter and am building my own scope. I have easy access to these materials and I am ready to coat my tube.

Regards Cristian

[rmcpb (Rob)]

Cristian, Anything to stop the surface being flat works, that is why I used the textured paint and others use felt or velvet. If you have the makings have a go and get back to us with the results we would love to hear about it.