Cost of getting a 12” mirror recoated

[5ash]

Hi , looking for a ball park figure for recoating a 12” mirror. I know sometimes you might just as well buy a new mirror sometimes. Regards philip:shrug:

[Saturnine]

Hi Phil
Try Palmway Optical in Forster/ Tuncurry. Great service and nice coatings but recoating in Oz is not cheap, cheaper than new these days though. Recently had an 250mm. mirror redone and am happy with the results.

https://palmwayoptical.com/

[Leo.G]

Second the mention to send it to Wayne at Palmway optics.
As for costs, only they can tell you that.


https://palmwayoptical.com/


I hope the link is permitted, sorry if not.


Replacement of a 12" mirror would be very expensive in comparison I should imagine. It used to be an 8" primary for the GSO Newt was around $200, now it's near cheaper to buy the entire scope new.


I've often seen mention here of boxes custom built to ship mirrors, I sent mine in one of the small safe cases, packed in custom cut foam (more butchered with a Stanley knife but definitely custom). The case has provision for locks (I used cable ties) so no one tampered with it and it couldn't possibly fall open in transit.
Suitable size cases can be had from Supercheap auto on occasion for reasonable prices and when the mirror gets back they double as an eyepiece/camera/anything astronomy case.

[gerardgallagher]

In terms of removing the old Aluminium coating, do they need to re-work the glass? Do they test the new finish / coating and print out the strehl and optics numbers on a certificate?

[Stefan Buda]

Coaters don't rework the mirror. You get it back with the same figure.
Even just providing a Strehl figure analysis would probably double the cost, let alone reworking it.

[Bobbyoutback]

Well said ! :thumbsup:

[OzEclipse]

As others have said, coaters don't rework the glass. They use a very strong corrosive solution to dissolve and remove the aluminium coating. Clean the glass first chemically then some follow up with an ion beam clean. I knew one aluminiser in the 1980's in Brisbane who used aqua regia, a mix of three parts concentrated hydrochloric acid to one part concentrated nitric acid. I don't know what Wayne Sainty at Palmway uses. The overcoating sits on top of the aluminium so when the aluminium dissolves, the silicon monoxide overcoat releases. It is chemically very similar to glass and neither the glass nor the overcoat react or are affected by the corrosive used.

Five years ago, I re-coated a 6" mirror that I hand made in the 1970's. The optical figure is excellent so just buying an off the shelf replacement was pointless. I had Palmway re-coat with an enhanced reflectivity aluminium coating with a silicon monoxide overcoat. The cost in late 2018 was $420 inc return freight. I paid the freight to them. Because I made the mirror and the quality of the optics, it was worth re-coating to me. An entire 6" commercial mirror would have cost much less that the re-coat but that wasn't the point.

I don't know how much a 12" mirror would cost to recoat, it would be at least $420 plus inflation plus some extra for the bigger mirror. Wayne is a nice guy and very helpful. Just contact him for a quote.

Joe