Durability tests on the Silver Coating / ミラー反射膜耐久性試験

The coating maker guarantees durabilities of the new silver coating as passing the tests of high-humidity and high-temprature, over 90 degrees centigrade with 90 percent humidity, soaking in the solt water, and etc. This time, I will also show you the results of the durability tests; one of my friend, a researcher of progressive telescopes, voluntarily has done on the silver mirror with other comparative samples.

 この特殊銀コートは、蒸着メーカーがその耐久性を、高温高湿テスト (温度90℃湿度95%中、1,000時間)や塩水浸漬テスト等で保証している画期的な物ですが、 私の友人がこれとは別個に数々の実験をしてくれましたので、ご紹介したいと思います。

Test 1: Durability against car exhaust( durability against sulfur dioxide);

Watched the possible damage of a silver coated mirror sample attached at the vent of a car by adhesive tapes after driving 60 miles (100km).

result: After washing the soot the silver mirror restored its flawlessly beautiful surface.

To accelerate the reactions, I changed the test substance from gas to liquid after that.


自動車の排気口に銀ミラー片を強力両面テープで張り付け100km程度走行後の劣化(の可能性)を観察。  (銀増反射膜のみ)

→結果 煤が付着するが、清掃後は全く劣化なし


Test2: Tape pealing off test;

Adhesive power from weak to strong, I tested the mirror samples by musking tape, heavy-duty paper tape, then strong double-stick tape.
result: No pealing off was occured on each mirror, silver, aluminum-A, aluminum-B.

テスト2: テープ剥離試験;


(銀増反射膜と アルミ増反射膜AとB)

→結果  銀・アルミA/Bとも剥離なし。

adhesive tapes used on the pealing tests

Test3:Durability against strong acid;

As the silver inherently has a tendency of going black under the sulfur dioxide, I tested the mirrors soaking in the spa water of hydrosulfuric acid.
Minami-Aso Jigoku-Onsen
(Jigoku-Spa in southern Aso; Spa of hydrosulfuric acid;PH=1.74 )
comp: the PH of our gastric acid is 1.5 to 2.
result: Every three of the sample mirrors survived flawless in 5 hours soaking.
Following table shows the resuls of more severe test of longer hours.

テスト3: 強酸耐性試験;


南阿蘇地獄温泉 硫化水素温泉 (PH1.74)
(銀増反射膜と アルミ増反射膜AとB)

test4:Durability against strong alkalies;

As aluminum is said to be erodent on the sodium hydrate, I have also tested the mirrors soaking in counterpart PH of 12.26, sodium hydrate solution.

result: After 14 hours of soaking, aluminum A had small holes, aluminum B caused almost total exfoliations.


アルミが水酸化ナトリウムに侵される性質があるため、  強酸とは逆の強アルカリPH12.26の水酸化ナトリウム溶液にミラーを入れ劣化を観察。
(銀増反射膜と アルミ増反射膜AとB)

Acknowledgement and Conclusion

I musn’t forget to extend my sincerest appreciaton to my friend who have kindly submitted these painstaking report to me. This will surely correct the stubbern stereotype against silvercoating and lead the astronomical world to the proper derection.

In conclusion, I can say with confidence that this enhanced silver coating more than meets the standard of durabilities of mirrors in the practical use of a telescope.


これらの大変骨の折れるテストを実行し、まとめてくださった私の友人(進歩的な 望遠鏡の研究者)に心より御礼申し上げます。

このリポートが従来技術の銀コートに対する根強い偏見を払拭し、天文界を正しい方向に 導いてくれることを確信しています。

このテスト結果により、この特殊銀コートが、天体望遠鏡用の光学素子としての耐久性の 基準を十分に満たしていることが確認できました。