Paint Flakes on Skywatcher 200P Primary

[SnakeyJ]

Any one had an issue with this before - I set up last night and good early views of Jupiter, but sadly cut short by one of the kids waking. By the time she was settled back it had gone midnight and clouding over, but the scope was quite heavily dewed up. I let it all dry out in the conservatory, but on cleaning down this afternoon saw some scary looking black marks all over the primary. Thinking the worst I stripped the mirror cell out to take a close look and this all appears to be black paint flakes (see attached - or there again it won't allow me at the moment, you can try via my public dropbox if interested https://www.dropbox.com/s/yxazp9vffi9vrdr/2012-11-11%2009.52.14.jpg - if not try to remember 101 dalmatians to get the idea).

No problems as it all came off under the tap and I managed to get the mirror back in with only very minor drying marks - but can't determine the source of the flakes. I wiped a few out of the tube, but nothing appears to be visibly peeling, the mirror support itself looked possible, but again nothing obvious.

Has anyone seen anything similar and is there anything particular to look at, or is it just a normal fact of life?

Telescope Skywatcher Explorer 200P, 3 year old last of the blue painted ones.

[jimmyjamjoejoe]

Eeeek that looks scary. If you can't see anything flaking i'd be inclined to believe it came from outside.

Are you sure it was paint? Looks like it could be ash from a nearby fire/chimney...

[dtr42]

looks like bonfire ash my car was covered in it 6th nov and that looks very similar

[SnakeyJ]

Unfortunately most the bits on the mirror were flushed straight down the kitchen sink, but the few bits I found in the OTA looked flat, matt black and had jagged edges. They were adhered to the mirror and wouldn't blow off, but came away after a minutes worth of running water.

Before being interrupted I was observing near the vertical trying to find andromeda, so could also have been some crud blown of the roof - though I don't recall it being breezy.

[SnakeyJ]

actually dtr42 might be on track, might have been some firework ash/residues - otherwise that volcano in iceland might have belched again!

[LukeSkywatcher]

They do look like flakes of black paint to me. They dont look like soot etc from chimney's. Glad you got rid of them. They would not have posed a big problem with observing, but i wouln't be happy with them.

[glowjet]

Snakey if you did not find it much of a hassle to remove the mirror, I would do it again, but this time rinse in distilled water, tap water will water stain, as it contains all sorts of impurities. By the looks of things to me, the particles look to have been airborne, floating about in the atmosphere from the last few nights of bonfires and fireworks

John.

[MrPloppy]

Could it be the flocking from the inside of the tube?

[SnakeyJ]

I haven't flocked this yet - I brought 3 rolls of DC-Fix courtesy of FLO, did my lad's Astromaster 130, then in a fit of compulsion brought myself another Explorer 200P and HEQ5 Pro mount from Ebay. I'll wait until this arrives and check it's ok, flock and keep the better of the two and then have to sell one. Otherwise no pressies for the kids this X-mas - Ho-Ho-No !

[SnakeyJ]

I will take the mirror cell out again and clean it with some destilled water as John suggested. if I can find any more flakes I'll try and get a decent close up image to post. It does seem a bit mysterious, given the flat irregular/jagged shapes and even colour, peeling paint was my main concern - but the coincidence with Bonfire night/Fireworks looks very plausible.

I can't tell you how relieving it was to see these bits flushed off, revealing a nice clean mirror.

[Liofa]

If its not stuck to the mirror, gentle strokes in the same direction with a soft lens brush

Should remove it. The mirror should have a silicon dioxide (SiO2) coating on it... Only the really high end scopes are purely Al finished. Could be bonfire ash I guess.

[zedds]

I had something similar on the primary of my 200p when it was new. I took it out to clean it and inspected the OTA and found bits of paint loose on the inside. Nothing major just bits along edges so i used a small dust brush to clear it before i put the mirror back. Not had a problem with it since.

[ollypenrice]

Funnily enough I found my Dob covered in a fair amount of black muck this week. It lives in a not very hermetic roll off. I'm in SE France but sometimes there's a lot of rubbish in the atmosphere and the storms have been tracking all over Europe recently. Who knows?

In any event things like drying marks are totally insignificant and not worth bothering with. Trying to get a mirror perfectly clean is a high risk activity with literally no benefits at the end of it. Reasonably clean is perfect. (At the 200 inch Palomar they apparently used to find cigarette ash on the mirror after Minkowski had been up in the prime focus cage all night... )

Olly

[SnakeyJ]

It took a while, but I finally tracked down the source of the paint flakes to the bottom of the focuser assembly - some horridly thick matt black paint applied poorly by Synta - will post some phots tomorrow.

[LukeSkywatcher]

Sounds familiar. The same thing happened to my secondary on my Heritage when it was new.

[SnakeyJ]

Just the promised photo of the focuser base:

https://www.dropbox.com/s/20uf50qvkdsivuu/2012-12-30%2011.05.10.jpg

Large blob of thick paint to the bottom of image, which was breaking/flaking away. I've chipped this all off now, so hopefully problem resolved.

Given the cost/performance of these OTAs new, you can't really complain about these minor quality control issues!