As well as putting them emulsion to emulsion you need to use a reasonably
heavy piece of glass - not picture framing thickness. And of course the
base must be flat as well - another sheet of plate glass is one way to
ensure this.
Of course if you are reasonably handy with tools you can make yourself a
contact printing frame fairly easily at low cost. I knocked one up in an
hour or two which clamps everything very firimly together. Doesn't look
much but does the job.
Peter Marshall
petermarshall@cix.compulink.co.uk