Platinum/Paladium printing

[Rickmartinsphoto]

Hi everyone!
I've been reading about these printing processes. All writers agree this is a contact print system, and if you want bigger prints the way to go about it would be to make a digital negative on acetate.
However i was reading an old book on the nudes Irving Penn made in the 40s, and it states that he worked with a Rolleiflex - yet he apparently produced some 30x40cm platinum prints!
Am I missing something?
It seems you cant focus am enlarger because the UV light used is a different wavelenght. But surely nothing keeps you from wasting a few small prints to find the correct focus, then insert the big paper?
You would have to work with some sort of "daylight lamp", if that exists.
Anyway, is the book wrong or is there a way to make platinum or palladium enlargements?

[cowanw]

You can make an enlarged negative with film, and then do your contact printing

[sanking]

Irvin Penn printed with enlarged negatives made on film. Today most people make digitally enlarged negatives.

It is possible to make enlargers capable of exposing negatives for platinum/palladium printing, but it takes a huge amount of light, special enlarging lenses, and very long exposures. Most people find it more practical to make enlarged negatives and make the pt/pd print by contact printing.

Sandy

[Mark Woods]

I think he enlarged the original neg and made a dup neg the size he wanted to make the print. I use to do that when those films were still made.

[Rickmartinsphoto]

Thats exactly it: where does one find a 30x40cm negative these days (if ever there was such a big format on acetate or estar base).
It occurs to me now that maybe it would be possible to make a paper neg. That would be employing two old procedures but it would work, no?
Sandy, if the exposure time is not a problem how do i focus the image using an ordinary lens and a UV lamp?

[Jim Noel]

If you are going to project the image,you need a quartz lens, not glass.

[Rickmartinsphoto]

Well that would complicate things, Jim Noel. Do these lenses even exist?
So the way to go is either by the book, meaning a digital neg; or a paper neg like Talbot used to make in the 19th century...

[rcmartins]

I have some experience doing enlarging for alt. processes contact printing. I do this, as previously stated, by enlarging twice the original neg. There are positive films, but my experience with those is still small. There are still films being made to sizes up to 50x60 cm. Depending on several things i have used Rollei ortho 25, Rollei ATO 2.1 and Ilford FP4 (Ilford also makes ULF Delta and HP5). If i want highest quality I make a first enlargement to the final size and then a simple contact pritn copy from interpos to neg. If I need to control costs I start to maje an interpos of the same size of the neg and then enlarge to the final size.
It requires some work and is not cheap, but I do prefer the work flow associated with the optical enlargement than making digital negs.
raul

[stawastawa]

It occurs to me now that maybe it would be possible to make a paper neg.

don't paper negs have a rather short DR though? so maybe stacking two paper negs? but then that would be a thick sandwich, and a bit fuzy!

[Rickmartinsphoto]

Thanks guys for the input!
True Stawastawa, as i plan to do portraiture paper negs are out of the question.
Obrigado Raul pela sua ajuda. Consegues achar este material em Portugal? It is indeed a very expensive process, and i can only think these film sizes are not going to be around long.