Question about ZWB or QB typical thicknesses

[Andrea B.]

In our list of recommended gear, LINKIE, I have of course listed the following stacks.

ZWB1 + QB39

ZWB2 + QB39

ZWB3 + TSN575

 

But I don't know anything about the typical thicknesses of ZWB glass sold on Ebay.  Also, does anyone have any recommendations for thicknesses of the IR-blockers? 

 

I will try to investigate on my own, but would also welcome any input from folks actually using ZWB stacks of any kind.

 

Thank you in advance.

 

[Stefano]

The most common thickness is probably 2 mm.

[photoni]

 

these are the filters i got from Tangsinuo, and the thickness i measured.
If I remember correctly @ulf measured them more precisely
 

 

QB39 = 1,6 mm - (similar to BG39 is too thin to block IR. with 2 together it works as TSN)
TSN575 = 2,25
QB29  =  2,1
ZWB3 = 2,15 (now oxidized - not usable)
ZWB2 = 2,15
ZWB1 =  2,2

 

in many of my posts you can see the results

[colinbm]

@photoni
As mentioned on UVP before, Phosphoric Acid will clean the ZWB filters. 

[photoni]

2 hours ago, colinbm said:

@photoni
As mentioned on UVP before, Phosphoric Acid will clean the ZWB filters. 

Thanks, I didn't read that. with what dilution?
does 10% nitric acid work?

[Akira]

A 28mm ZWB2 I bought recently from amazon is 2mm thick.

[ulf]

8 hours ago, photoni said:

 

these are the filters i got from Tangsinuo, and the thickness i measured.
If I remember correctly @ulf measured them more precisely

My thickness-results are at the very last post of this thread, not only for Chinese filters, but also American made:

https://www.ultravioletphotography.com/content/index.php?/topic/5518-new-tangsinuo-filters-which-to-get/page/2/#elControls_61509_menu

 

The thicknesses can have a rather wide spread and if not clearly stated, that is a problem as the thickness is just as important as the filter glass material used.

I think that is partly due to ignorance of the buyers not asking for that information causing a distinct demand.

 

The exact thickness might not be that important, one tenth of a mm more or less for normal photography will be OK.

 

Some of the bad reputation for Chinese filter glass, beside batch spread and possibly bad mechanical manufacturing might be that comparisons were made without any attention to the thickness.

[otoien]

The recently purchased QB39 from Tangsinuo in 20mm diameter size is 2mm thick (or perhaps 2.05mm), . The 20mm diameter ZWB1 I purchase long time ago from ebay seller mei-2014 is also 2mm thick. The IR leakage of the combination seems minimal, beyond any practical effect (see this thread: https://www.ultravioletphotography.com/content/index.php?/topic/5818-opportunistic-reflected-uv-with-planetary-astrocam/#comment-62320).

[Wayne Harridge]

On 5/27/2023 at 2:53 PM, photoni said:

Thanks, I didn't read that. with what dilution?
does 10% nitric acid work?

I have an oxidised filter too, just wondering if you can use Coca-Cola to remove the oxidation as I understand it contains phosphoric acid and it does seem to clean up things like tarnished coins.

 

[Andy Perrin]

Cadmium used to recommend hydrogen peroxide soaks for oxidation. 

[Andrea B.]

holy heavens!!

Please do NOT use nitric acid or phosphoric acid to clean your filters. You could as easily corrode the glass as clean it depending on how strong the acid is !! Not to mention what it might do to your skin if you splash it. Acids might also react with the filter mount.

 

If the oxidation is not too advanced, oxidized blue-green filter glass can be soaked overnight in hydrogen peroxide to remove it. Or you can polish the filter with very fine-grained cerium oxide glass polish if the filter is not coated. Glass polish is a little messier.

[colinbm]

5 hours ago, Andrea B. said:

holy heavens!!

Please do NOT use nitric acid or phosphoric acid to clean your filters. You could as easily corrode the glass as clean it depending on how strong the acid is !! Not to mention what it might do to your skin if you splash it. Acids might also react with the filter mount.

 

If the oxidation is not too advanced, oxidized blue-green filter glass can be soaked overnight in hydrogen peroxide to remove it. Or you can polish the filter with very fine-grained cerium oxide glass polish if the filter is not coated. Glass polish is a little messier.

Andrea, Phosphoric Acid is used to cleanup the glass filters OK.
It is not a strong acid & with care to not get it on your shin. People consume it everyday, in the correct application !
Works well for me & should be finished cleaned with Hydrogen Peroxide.

[Andrea B.]

Col, thanks for the update.

I was remembering my days in my college chem lab seeing bottles of thick, strong phosphoric acid. I took 4 chem courses as an undergrad (basic, analytic, organic), but decided not to pursue it further.