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Lee 729 Cleaning warning

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#1 dabateman

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Posted 10 September 2019 - 16:40

I just tested cleaning a section of Lee 729, scuba blue with some 99.9% isopropyl alcohol (IPA) that I usually use to clean some glass and my camera sensors.

DO NOT USE this on the Lee filters. It dissolves away the blue. You can see it lifting onto a Q-tip. This may be an excellent way to create a cloudy or frosted filter. But if you want good image quality all will be blurry after cleaning with IPA.

#2 Cadmium

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Posted 04 October 2019 - 01:29

The polyester filters (Lee, Rosco, such as 729) are clear polyester film with dye on the surface.
I recently had occasion to separate a glass/poly lamented stack, which was submersed in a methylene chloride bath for 3 days to dissolve the UV cured glue.
The lamination all came apart, the methylene chloride was turned the color of the filter from the dye mixing with it, yet the polyester film was left completely intact, except it was now completely clear with no color.
Even special glue needs to be used for such filters, otherwise the glue can smear the dye and make it uneven and blotchy.
I have not tried IPA or any other cleaners, but the dye is definitely sensitive to solvents. The polyester sheet may also be sensitive, but not to the methylene chloride, which I was surprised about,
however, it doesn't make much difference if the clear sheet is intact or not, it is of course of no use to me once it is clear.

It might be interesting to try separation of a Tiffen filter, for example, being all Tiffen filters are laminated film stacks, such as the polyester/glass stack I was separating,
just to find out if the film used in the Tiffen filters are surface dyed, or perhaps the color is integrated into the film used.
Even if their film is surfaced dyed, it is hard to say if the dye is the same in the sense of sensitivity to the same solvents.
However, if the same kind of clear sheet was left intact, then one would know the sheet is not colored internally, but instead surface dyed like the Lee/Rosco filters.
But I would need to find some half way destroyed Tiffen to test this on first. :-)
And the same could be tested with a Schott KV filter, but no way will I be testing that on my KV filters. :-)

Edited by Cadmium, 04 October 2019 - 04:41.


#3 dabateman

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Posted 04 October 2019 - 08:27

Interesting about leaving a clear polyester film. You could use that to make a UV lens protection filter, to allow UV through. Or just use a lee clear filter.

Seems that if you mess up a lee filter, the best thing to do is just cut a new one.

#4 Cadmium

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Posted 04 October 2019 - 09:48

If you want a UV?Visual?IR clear filter for a lens, then there are much better choices.

Right, the Lee filters are too inexpensive to worry about. Just cut another one off the sheet.