Flocking telescopes

[haitch]

Right, now I'm getting over my issues with mirrors it's time to think about putting the old girl back together. Before I do I'd like flock it.

Now it's a 14" so the tube will be about 40cm Diameter and the tube length, at a guess without actually measuring it, is around 1.5m so I'm talking something in the region of 2 sq m to fully flock it so something like protostar is out of the affordability range.

Any thoughts on what else I might use CHEAPLY? I've heard there is some stuff in craft stores and Ebay - has anyone any experience?

Is it worth a complete flocking or should I just flock the upper end of the tube? (it'll be an interesting process flocking the middle part - I think I might have to send the kids down the tube )

Cheers for any thoughts

Paul

[mik]

Hi Paul,

I flocked my XLT150 with felt sheets from Hobbycraft they are about 20p each and A4 in size, they do self adhesive ones for £1 each, but opted to glue mine in with evostick extra sticky PVA glue.

Here is a pic you can see a slight overlap because i was lazy.

Mick.

[haitch]

Hi Paul,

I flocked my XLT150 with felt sheets from Hobbycraft they are about 20p each and A4 in size, they do self adhesive ones for £1 each, but opted to glue mine in with evostick extra sticky PVA glue.

Here is a pic you can see a slight overlap because i was lazy.

Mick.

I do lazy too!

I was wondering about glue (if not self adhesive). Obviously it needs to be sticky enough to hold, flexible enough to not break off when temperatures fluctuate and no nasty chemicals to damage the mirror coating (presumably they don't like solvents?). I suppose the glue it yourself option is also better on the latter of those as you don't know what might be in the glue on the self adhesive ones.

Did you do anything to prevent shedding?

[Starflyer]

I used self-adhesive felt when I flocked my Skywatcher 130pm, it was very stick stuff. It did start shedding a very small amount of tiny black fibres so I stripped the mirrors out and gave the felt a spray with matt black paint. That 'locked' the fibres in place and it looked just as dark.

If fact here's the thread and there's a link to the company I got the felt from about half way down.

[mik]

Hi Paul,

Yes to prevent shedding i sprayed the inside with spray varnish from my local Games Workshop hobby store its about £5 a tin,

It took me about 2 weeks to take apart,flock,varnish and put back together.

Due to my bad back last winter now better i never used it but it is on the patio cooling as we speak.

Mick.

[George]

Hi Paul,

I flocked my XLT150 with felt sheets from Hobbycraft they are about 20p each and A4 in size, they do self adhesive ones for £1 each, but opted to glue mine in with evostick extra sticky PVA glue.

Here is a pic you can see a slight overlap because i was lazy.

Mick.

Got mine from Hobbycraft too, actually mine was on a roll about a metre or so from memory.

[Astro_Baby]

I used protostar stuff - I really didn't want the hassle of having to spray it down or have the stuff shed hairs all over the insides. The Protostar stuff wasnt that expensive I thought.

[albedo0.39]

I went the Hobbycraft route as well, but opted for the felt on a roll. First off, I removed all the gubbins:- Spider, supports, mirror cell from U and L OTA. (brave I know) then calculated the size.

I layed it out on the floor and cut to the right height and length (+ a bit for overlap) and then proceeded to paint the inside of the U / L OTA with waterproof PVA (cheap as chips from Hobbycraft).

Following this, I then carefully laid the flocking over the glue, making sure I used additional glue as required to make it a very strong bond. Once dry, I took a No.10 scalpel and trimmed it to the right size and then re-fitted all the fittings back onto the scope. At this point, I took huge efforts to make sure the spider was exactly central to the U OTA.

It looks a treat, makes a difference and cost almost £10 for the whole lot. You also need to be aware that the felt from Hobbycraft definately has 2 sides to is and one is certainly better at absorbing light than the other.

Good luck

[haitch]

I used protostar stuff - I really didn't want the hassle of having to spray it down or have the stuff shed hairs all over the insides. The Protostar stuff wasnt that expensive I thought.

I guesstimate needing 6 sheets 50cm x 71cm at £10.95. I would like to use it but it's a bit over my budget given what I've been spending lately unless anyone knows where I can pick it up cheaper (I'm struggling to find places Googling it).

[red dwalf]

bought my Protostar flocking paper from an SGL member "johninderby" very good, very adhesive and full instuctions, flocked my 130 newt and it looks brill.

[Astro_Baby]

The site I got mine from doesnt appear to exist anymore

[FLO]

Perhaps it was from here: Telescope Parts UK

[Astro_Baby]

Thats the one - they must have changed domain names I guess - thanks Steve.

[barkis]

I only ever flocked one of my scopes. The 12" f6.

I used Wood Chip paper stuck on with PVA, and painted with Matt Black Emulsion paint. Good job too.

Ron.

[mik]

I only ever flocked one of my scopes. The 12" f6.

I used Wood Chip paper stuck on with PVA, and painted with Matt Black Emulsion paint. Good job too.

Ron.

Just like my lounge.

[albedo0.39]

Just like my lounge.

LOL

[barkis]

Just like my lounge.

WHAT!! Black?

Ron.

[haitch]

I was putting every combination of "jet ultra black flocking fabric" through Google last night and discovered that home cinema enthusiasts have a similar interest in light absorbing materials around their screens.

Has anyone ever tried velvet or fablon velour? These seem to be in common use by Audio Visual brigade and I wondered if they might not shed fibres too badly.

[daz]

I did my 8" in Protostar from John as well. No shedding and absolutely no stray light!

[haitch]

Does John retail it then?

I had no idea - I just thought someone had bought his spare off him.

I'll give him a pm.

Cheers

[acey]

Is it worth a complete flocking or should I just flock the upper end of the tube?

The traditional approach is to flock every part that is visible through the focusser tube (without eyepiece), since that's where the unwanted light is. This of course means also paying attention to the region beyond the end of the tube (i.e. inside your home-made dewshield).

[haitch]

The traditional approach is to flock every part that is visible through the focusser tube (without eyepiece), since that's where the unwanted light is. This of course means also paying attention to the region beyond the end of the tube (i.e. inside your home-made dewshield).

Am I getting carried away then thinking I need to flock the whole tube to stop light bouncing off the sides and reaching the primary?

[acey]

Flocking the whole tube is going to have more effect than only part of it, but the question is how much you gain for the amount of work and expense. I don't know of anyone who has tried doing actual measurements on the effect of flocking all or part of the tube (can anyone offer a link?) but when I flock my 12-inch flextube, I plan on only doing the part under the focusser. If I still see signs of stray light issues then I'll think about taking further measures.

The signs include inadequate contrast on planets and excessively bright diffraction spikes around stars, both of which I have at present (compared to my 8-inch). The flextube is open at the middle, and from a dark site it makes little difference whether I use a shroud round that part - its purpose is to prevent dewing. From light-polluted areas with a lot of unwanted direct light it's a different story - maybe flocking the whole tube would be useful in those situations.

I should add that I see a major difference in stray light at the eyepiece when using a dewshield with a reflective interior - this underpins the importance of thinking about the region that's actually sending light into the focusser.

[haitch]

Flocking the whole tube is going to have more effect than only part of it, but the question is how much you gain for the amount of work and expense. I don't know of anyone who has tried doing actual measurements on the effect of flocking all or part of the tube (can anyone offer a link?) but when I flock my 12-inch flextube, I plan on only doing the part under the focusser. If I still see signs of stray light issues then I'll think about taking further measures.

The signs include inadequate contrast on planets and excessively bright diffraction spikes around stars, both of which I have at present (compared to my 8-inch). The flextube is open at the middle, and from a dark site it makes little difference whether I use a shroud round that part - its purpose is to prevent dewing. From light-polluted areas with a lot of unwanted direct light it's a different story - maybe flocking the whole tube would be useful in those situations.

I should add that I see a major difference in stray light at the eyepiece when using a dewshield with a reflective interior - this underpins the importance of thinking about the region that's actually sending light into the focusser.

Thanks for that, it's all getting a little clearer now. I think my choice will probably have to be between partial flocking with protostar or complete flocking with an alternative on price grounds. Given that I observe most of the time from a light polluted garden I think I need to fully flock.

[philsail1]

Haitch,

I "Flocked" a Skywatcher Explorer 8" Newtonion a couple of years ago with a roll of jet black "velour/felt" type of flocking paper with an adhesive backing. This was obtained from "Hobbycraft" (www.hobbycraft.co.uk) at Chester for £4.99p for a 150cm x 45cm roll. This is very black and has a raised "nap" surface. I wasn't happy about the prospect of trying to apply the sticky backed stuff to the inside of the scope's tube. I decided to use a thin white card, and stick the velour to the card and slide the card inside the scope's tube. I prepared everything as much as I could beforehand. Placing a large piece of hardboard on the carpet to work on was the most important part of the job. I tackled the main mirror end first - as it was the easiest, with only this item to be removed. The whole job took me about 3 hours to complete. I left re-collimating the telescope until the next day. Surprisingly, collimation was very little astray. My home made "film cannister" cap and final precise check using FLO's Cheshire Collimator set it all up nicley. I had to play about a little twisting the "vanes" of the very thin "spider" to ensure they were edge on to the main mirror. So I had no glue on the inside of the tube, and if I ever wanted to renew the flocking, all I had to do was slide the cardboard tube out of the scope's tube.

Best wishes with whatever method you choose to "flock" your scope.

Regards,

Philsail1.