I am using an Epson 4490 scanner. I have a large pile of warpped negatives that won't lie flat. Does anyone know of better negative carriers that may be available?

It sounds like you might need to use anti-newton glass. Try here:
http://www.fpointinc.com/glass.htm

Blue Dog

Try to find some glassless negative carriers from old enlargers. When these are stripped down you finish up with a metal plate with a hole in of the correct size.
These can be placed over the negative and will hold them flat.

I have plates of all sizes up to 5x4. They could also be made from cardboard.

Hope this helps

Ken.

If you are just going to use a sheet of AN glass, make sure to cut out a mask from 1 mm material so that you get the film close to the right suspension height. Use your current holder's outline as a template and make sure to include the calibration notch at the top. Otherwise, you will have problems.

Doug

This might be overkill, but it's still an interesting link
http://www.scanscience.com

i highly recommend that if you are using a normal flatbed scanner for photos and negatives and slides and doing a lot of negative/slide scanning, that you invest in a dedicated negative/slide scanner. i really have no data on flatbeds that do negatives and slides, but to me, it's sort of like one of those all in wonder shop tools you buy. they claim to do everything, drill, saw, plane and so on, but do none of them well. i dont know that that is the case with flatbeds and negatives, but given the option and the budget, i'd go with a dedicated negative/slide scanner.

craig

I agree fully with Craig. You won't be able to match the quality of a dedicated neg/slide scanner with a flatbed w/ adapter. If you do not want to invest in a new one, there are a lot of lightly used ones for sale by people who went digital but needed to scan their existing archive of slides and negs.
Regards, Murray