Best packing method for 20" mirror?

[Insomniac]

Any ideas as to the best way to pack a large mirror for re coating? Mines going to have to go from N.Z. Any strong opinions out there as to who (in Australia) does the best enhanced (dialectric) coatings?
Any guidance greatly appreciated.
Chris

[Rick Petrie]

Not too long ago I had my mirrors recoated in Sydney by Isaac Qin from
C.Qin Pty Ltd. (advertises in Australian Sky & Telescopes)
Did an excellent job of aluminizing with a quartz overcoating.
Has done many top jobs for well known imagers and others.
If you wanted to contact him :-

PO Box 100
Croydon Park NSW 2133
Australia

10 Clissold Parade
Campsie NSW 2194
Australia
Tel: 61-2-9789 1047
Email: icqin@hotmail.com

Worth a go. I am very happy with mine.
Cheers Rick

[Ian Robinson]

I'm not sure if you can get ultra high reflectivity dialectric coating with TiO2 protection done here in Australia. if you find someone who does it here I'd be interested in knowing who they are.

Packing , double pack in boxes , using high density styrofoam coat to give a tight fit to the edge of the mirrors and layer it to the same thickness as the mirror, greaseproof paper sheet wrapping mirror.

Did you keep the boxes the mirror came in ?

I think there was a link provided here a couple of months ago that explains mirror packing for shipping.

[Insomniac]

Thanks for your advice on packing. Check out this Nov/Dec S & T mag for ultra high reflectivity coatings done in Australia by Optical Coatings Associates. They seem to be a reputable bunch and have responded in detail to lots of my technical questions.

[Satchmo]

What price did you get for a 20" mirror enhanced coating ?

[Ian Robinson]

:thumbsup:bookmarked their url for future reference.

[Insomniac]

$800 plus small change (in comparison!!) for stripping off the old coatings was what Optical Coating Associates quoted me for my 20". GST & shipping to & from N.Z & GST will match that!! My only alternative here is an aluminium coat with no protective overcoat. Much cheaper, but just how long it would last with dewing I hate to think.

[leon]

There is only one way to pack a mirror for any sort of transport.
One has to make a special box to house it, a few millimeters of the exact mirror size out of a sturdy timber construction.

In that box put in a small piece of wood, say the size of a match stick, in each corner, and place the mirror up side down on those match sticks, do not wrap, and screw the lid down with some card board in between the lid and the mirror.

you do not wrap mirrors. :scared:

Leon :thumbsup:

[Satchmo]

Wrapping a mirror in clean ( ideally acid free ) tissue paper is perfectly safe , as long as you then place a cardboard disc over the tp plus some packing to stop the tissue moving against the surface during shipping. 99% of ceommercial optics would be shipped this way.

Resting a mirror on its chamfer at four pressure points to isolate the surface is far more likely to lead to damege.

[ausastronomer]

Ian,

If ever I buy a mirror off you please leave the greaseproof paper on your kids lunch and put some "acid free tissue paper" over the mirror you send me.

You can buy acid free tissue paper at any craft store. James Mulherin from OMI, who ships more mirrors than anyone in the USA, ships all Obsession mirrors this way.

Cheers,
John B

[Ian Robinson]

Well, not exactly grease proof , was not sure what to kind of paper to call it and kind of paper came to mind :shrug: , someone else here nailed the stuff I was referring to (see Satchmo's post).

Fortunately for me, when my mirror arrived , I kept the shipping materials and resealed the the double box (less the mirror) for future use .... my mirror is currently stored in its original box, and my secondary is repacked , pending my getting around to reassembling my OTA. (a few minor mods on the new mirror cell - side clamps need mods (to make them function like a NOVAK RQ Mirror Cell's side clamps - only thing I can fault Orion Opticals Cells on is the side clamps .... they are strange screw-on monolithic machined from a bit of aluminium block beasties and don't fit quite right on my mirror .... not a big issue , just a fiddle fixing), a bit of flocking (maybe some light baffleling), and then reassembly , collimation and it'll be good to go under the stars on it's new home mount.

Re packing material - I would think Balsa wood blocks or wedges (very soft stuff with lots of give, maybe it's a generational thing, you fellas today probably never do stuff in Balsa wood) would be suitable, or good quality styrofoam would be OK to protect the edge from damage.
But then I guess it comes down to the mass of the mirror and the hardness of the mirror surface or the coating (or SiO2 or TiO2 or what have you's protective overcoat's hardness , so long as the packing is softer than these you should be fine unless some hard grit gets between the surfaces.

I was also under the impression the more reputable coaters we only too happy to advise on best packing for mirror shipping , all you need to do is ask them if it's not already in their FAQ or explained in their website .

[BerrieK]

Umm... if you could pack the mirror as described in the thread , along with the rest of the 20" inch scope, and send it to my house I think that it would be best for everyone.

[Glenhuon]

When i sent the 10" away to get recoated i was advised to just pack it in a strong cardboard box wrapped in foam. Didn't like the idea, Aus post could break an anvil. Made a 12mm plywood box 25mm bigger all round than the mirror, rested it on its back on 12mm dense foam, covered the business side with tissue and more 12mm foam on top, with strips of foam around the sides to stop movement. then screwed the lid down and struck lots of FRAGILE stickers over it. Survived the two way trip nicely :)

Bill

[Insomniac]

My most recent advice from one of the Australian coating outfits, is to rest the mirror (surface down) on 3 equally spaced triangular wooden wedges glued/screwed in position on a board. If positioned appropriately, the mirror edge can be made to rest on the slope of each wedge. When this is done, a further 3 wedges can be pushed in against the mirror and glued down. Only the rear of the mirror actually gets anything flush against it. Any comments?

[Satchmo]

I just don't see the logic in placing the weight of a large heavy mirror on a handful of pressure points at the edge , particularly considering the G forces that glass might experince if it is dropped hard .

Given an acid free tissue paper wrapping and encased in polystyrene foam sheets inside a wooden box , what is actually going to damage a coating? . Overcoatings are as hard as glass and unless you've got some sand rattling in between your mirror face and the tissue paper it is perfectly safe.

If I were shipping a large personal glass mirror overseas I would look at how the commercial operations were shipping new mirrors , and that is wrapped in flat tissue surrounded by polystyrene foam sheets ( and I have some experience in this) Just my 2C.

[skies2clear]

I'd take Satchmo's advice on this, especially for a 20" mirror which is likely to be 2" thick or less. Years ago, many mirror boxes were made with 3 wooden wedges at the outer edge, with mirror facing down onto these, but remember, these mirrors were usually not very large (6", 8", maybe even 12"), and had diameter to thickness ratio of 6:1, so it probably wasn't much of an issue. But these days with thinner mirrors, I wouldn't take the chance packing this way.

My 2 cents..

Clear Skies

[Insomniac]

Thanks for all your comment & help on this packing issue. I suppose if the wedges were such a good idea, more mirrors would arrive on them from the manufacturers!