Re: [tech-3d] blueprint

[Peter Homer <P.J.Homer@xxxxxxxxxxxxx>]

>Zyla Nuite wrote:
>> does anyone know the iso # of blueprint paper?
>> 
>
>Blueprint paper (aka cyanotype) needs to be exposed to ultraviolet
>light.  I doubt it has an ISO rating like silver gelatin paper (which
>is not the same as the ISO rating of film).
>

I dont know if this is of any help but I once made blue slides on Diazochrome film which also needs exposure to UV. We used to start with high contrast negatives on orthoagfa (25 ASA) and expose to UV for 3 minuets on the light box with emulsion side up and the Diazochrome placed on top emulsion side dowm. I have no details of the intensity or wavelength of the UV source but it was intended for that purpose. We then "developed" in ammonia vapour the intensity of the blue depending on the ammonia concentration which should not actualy come into contact with the Diazochrome film, I am not shure if this is the same process as cyanotype blueprints,  P.J.Homer 




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