Dichroic filters: Shoud these be cleaned or not?

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I have used a Durst M605 Color enlarger for three years, but not on a daily basis. After this initial working period, the enlarger was boxed and has remanined so for the last 15 years.

I recently unboxed the enlarger and I want to use it in my darkroom. While cleaning the enlarger's head I have noticed that the yellow filter is dull, whereas the other filters look clear but they show some kind of deposit that look like specks of dust. I have tried canned air to remove these, but I was not succesfull. Judjing by its appearance, if it were on a lens, I wouldn't have any trouble using lens cleansing fluid to clean the surface of the filters... but considering the delicate nature of the dichroic filter I am a bit hesitant.

I have asked arround (in other forums) and was advised to be prudent. I contacted Durst's Support here in Portugal and was told that I could clean the filters with cleaning fluid, but I am still a bit hesitant.

Does anyone have any experience with cleaning dichroic filters? Any comments or experiences are most welcome.

Thanks in advance.

Luis Marques lmarques@netmadeira.com

Right now I am not sure if I sh

-- Luis M Marques (lmarques@netmadeira.com), January 04, 2002

Answers

Greetings,

I don't know how easy or advisable it would be to clean the filters, but I would look at replacing them instead. In addition to surface contamination, mold, etc., dichro filters can and do change over time. They can fade and from your description, that appears to be what happened. Good luck.

Regards,

-- Pete Caluori (pcaluori@hotmail.com), January 04, 2002.


The Manual for my Durst L-1200 suggests cleaning the filters with alcohol. The manual for the M605 may give a clue. You may be able to find it on line if you do not have it.

Fred

-- Fred De Van (fdv@mindspring.com), January 04, 2002.


My m605 manual does not mention cleaning the filters, i'd like to hear if Durst offers replacements for these when you find out

thanks & good luck, Joe

-- Joe Holcombe (joe1013_@excite.com), January 07, 2002.


Thank you all for your input. Here is how I cleaned the filters. and a couple of links I found while searching for answers.

Joe, I am not sure if Durst offers any replacement filters. Actually I did not find that out from their representative here in Portugal.

Last weekend I decided to go ahead. I was not able to disassemble the filters/dials assembly, and because of this I did not gain access to each filter individually. I felt however that it would be better to clean the filters as much as I could (I could only clean the yellow and part of the magenta - actually the filters/parts of filters that needed cleaning). I proceeded as follows.

1. I roughly undid the cotton swab tip, so as to give it a "cotton candy" appearance and I used it to gently remove first the liquid (2) and later on the alcohol (3) from the filter. I used the outer part of the cotton and avoid contact or pressure on the surface of the filter.

2. I tried lens fluid on a very small area first, and as I noticed the filter did not loose any color properties I decided to proceed on the whole surface.

3. The result did not satisfy me. I decided to try alcohol, adopting the same precautions. In my opinion alcohol is better, I got better results with it.

The filters are practically clear now. I say practically because both the lens fluid or the alcohol dry out unevenly and still leave slightly dulled patches. I feel those patches can be easily removed, but I would have exert more pressure on the surface of the filter and probably I would end up scratching it. Besides, as Ken pointed out, we are talking about a diffusion enlarger, and these small patches will have no practical effect.

The deposits that I spotted in the magenta filter came out easily. These were probably specks of dust that adhered to the surface of the filters.

I am attaching a link to a web page on Dichroic filters you may find useful. http://www.highend.com/news/dichroic.html

Also during my search for answers I found a very informative page on Halogen and Incandescent Lamps at http://www.lighttrader.com/ResourceGuides/HalogenIncandescentLamps.htm

Regards,

Luis

-- Luis Marques (lmarques@netmadeira.com), January 13, 2002.


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