I use an old LPL 66 condensor enlarger with a filter drawer. Inside the filter drawer is a piece of heat absorbing glass. When I use multicontrast filters, I usually put the filters directly under the heat absorbing glass. During one long exposure the filter stuck to the glass because of the heat. Am I supposed to use the filter without the heat absorbing glass on top? Or will it only be worse if I took out the glass and put the filter directly under (but not touching) the bulb?

Thanks for your replies.

jorge andrada

-- jorge andrada (glamour@mozcom.com), May 14, 2001

Answers

I don't know anything about the LPL 66, but heat absorbing glass does just that- it absorbs heat and gets hot so your negative doesn't. You don't want the filter to be in contact with it, and ideally the filter should be underneath it. It might be possible to make a little frame out of mat board to separate the two, or possibly the enlarger has an extra shelf in the drawer or nearby to hold the glass. You really want to keep the heat absorbing glass to reduce negative pop.

-- Conrad Hoffman (choffman@rpa.net), May 14, 2001.

Jorge: I'm not familiar with the LPL 66 enlarger, so what I have to say is pure speculation. The filter drawer seems to be a rather odd place to put the heat absorbing glass. If I were you, I would check and see if there is another place in the enlarger where this glass should be placed.

-- Ken Burns (kenburns@twave.net), May 14, 2001.

The heat absorbing glass does exactly what it says. It absorbs infrared (heat), and in doing so, it gets hot! Anything in contact with it runs the risk of partial melting. This will be true, whether the contact is with the top or the bottom of the glass. What you need is a spacer to keep the filters from contacting the glass.
I suggest you bend a simple little wire square from something like garden wire. Place the filters under the wire, and then put the heat absorbing glass on top, with the wire separating the two.

-- Pete Andrews (p.l.andrews@bham.ac.uk), May 14, 2001.

Jorge, I just bought an used LPL 66 and it didn't have any glass in the filter drawer. I bought a set of Ilford filters and cut them down. I tried out everything yesterday and had no problems at all, with the filters or the negs heating up. I would suggest taking the glass out.

-- Randy Belyk (randybelyk@home.com), May 14, 2001.

Jorge, Those filters will survive much longer if they are kept between two glass sheets, not only to heat, but also finger prints, fading, dust, etc. Mine are lasting years this way. Good printing.

Cesar B.

-- Cesar Barreto (cesarb@infolink.com.br), May 14, 2001.

Hi...my first enlarger was a LPL 66. It _had_ the piece of heat absorbing glass. I broke the glass about a year after getting the enlarger. I used the enlarger for about two more years without the glass. During that time I made thosands of prints using the same set of filters. Looking at some of the prints today I know I would not be able to tell which were made with the glass and newish filters and which were made without the glass and filters that were scratched.

-- Jim Vanson (p645n@hotmail.com), May 15, 2001.

I guess out goes the glass :-).

Thanks for the advices.

-- jorge andrada (glamour@mozcom.com), May 15, 2001.