I am going to build some horizontal cold head enlargers (6cmx9cm thru 4"x5" or 5"x7" and something larger to cover 8x10 and maybe larger 11"x14" because I have huge monochromatic lens that was made for 15"x21" film and I just want to do it.

1) Low budget

2) I'm in no hurry

3) That's just the way I am - if I can build something myself, I try. Sometimes this violates rule #1 above, but I learn something in the process.

4) If someone tells me something can't be done, that's one more reason for me to try.

5) A whole lot of other odd reasons we don't have bandwidth for.

6) It keeps me off the street.

I have read another post about the evolution of the Aristo light source and
have some questions.

I had focussed (haha) on a multi-tube blue fluorescent source of 420 nm (unless I can find an economical serpentine lamp source; not likely) with individual electronic fluorescent ballasts (dimmable) diffused thru white opaque acrylic. I have a foot lambert photometer and between adjusting the output of individual lamps and rear mounted reflectors I'll work on getting even illumination thru the optics.

Using a lamp with a strong 420 nm spectral component, I am assuming graded contrast paper will work and is still available.

I understand VC paper is used by somehow determining how much exposure with blue and how much with green. I'm not sure if this is measured and calculated or trial and error. What I don't understand is how the two different emulsions produce different appearance...is one 'faster' than the other and one is for dark and one is for light...kind of like the printing side of Zone method?

Is it possible to get a decent range of density with blue light only and graded paper (if it's still made)?

Thank you