Coating removal of a T400

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allhoest
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Coating removal of a T400

Post by allhoest »

I'm preparing a trial with a big scope, a newton D400 mm.

Removing the coating is not a new topic, but it is still a kind of special event.

Here, some pics of the process. Keep in mind the safety and environment protection.

Fitting the mirror in a box made for the purpose, protecting against leak with plastic sheets.
Protection of the area where the mirror has been stripped.
Pouring Iron(III) chloride (40%).
This time, the stripping was very fast; it took about 1 hour. The coating was not of very high quality.
The iron chloride is collected back, the mirror cleaned with water and the used material collected for disposal.

Alex
2022-08-04



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Re: Coating removal of a T400

Post by pupak »

I recommend that you mattify the back of the mirror by etching it with hydrofluoric acid. The matte surface prevents parasitic reflections and significantly increases contrast. Unfortunately, it slightly increases heat absorption.


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Re: Coating removal of a T400

Post by marktownley »

Job well done Alex!


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Re: Coating removal of a T400

Post by banjo »

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Re: Coating removal of a T400

Post by allhoest »

pupak wrote: Tue Aug 09, 2022 5:52 pm I recommend that you mattify the back of the mirror by etching it with hydrofluoric acid. The matte surface prevents parasitic reflections and significantly increases contrast. Unfortunately, it slightly increases heat absorption.
Thanks for the tip.
It is slighly matted. I have tried the mirror yesterday, but the seeing was not good.
I'll try imaging again with better seeing.
And compare with a 300mm.

CS
Alex


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