From: Jack Brubaker (jack@jackbrubaker.com)
Date: 02/07/03-01:05:12 PM Z
Considering the physics involved here the negative being just as good a
block of air flow as the poyester the limiting factor is how many feet of
edge needs to be sealed. With a continueous poly sheet over the neg there is
one perimiter to seal. With the neg acting as its own vacuum skin one must
seal both the perimeter around the paper and the perimeter around the neg.
Twice as many feet (roughly) of open edge. If it was important one could
have a standard skirt of plastic that was taped (continueous around the neg)
to the neg. It would then act the same as the neg-poly backing sandwich
without the extra layer in the light path.
Jack
> From: Dave Rose <cactuscowboy@attbi.com>
> Reply-To: alt-photo-process-l@skyway.usask.ca
> Date: Fri, 07 Feb 2003 10:55:30 -0700
> To: alt-photo-process-l@skyway.usask.ca
> Subject: Re: Homemade vacuum easel
>
> No, because the polyester must press against the negative/paper to ensure
> intimate contact between them.
>
> As far as I can tell, the polyester does not degrade the quality of light or
> resultant print quality. Dust on the polyester is not a serious problem.
> I've seen no apparent difference between prints made on my vacuum easel and
> those made in a conventional glass contact frame. It should be noted that a
> vacuum easel is much better for making large prints. Achieving uniform,
> intimate contact between (large) negative and paper is more difficult using
> spring-loaded glass contact frames.
>
> Dave in Wyoming
>
> ----- Original Message -----
> From: <Ender100@aol.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Friday, February 07, 2003 9:07 AM
> Subject: Re: Homemade vacuum easel
>
>
>> would there be a method where you could use the polyester just over the
> holes
>> that aren't covered by the negative and paper? Say by using four strips
> of
>> polyester? That way the polyester would not affect the image or provide
>> another layer to trap dust? Or maybe it doesn't matter.
>>
>> Mark Nelson
>> In a message dated 2/7/03 10:54:08 AM, cactuscowboy@attbi.com writes:
>>
>> << To use, place the negative & paper underneath the polyester and turn on
> the
>>
>> vacuum. The polyester will be drawn tightly against the pegboard,
> providing
>>
>> excellent contact between negative and paper. Bring the vacuum easel to
> the
>>
>> light source and make the exposure. >>
>>
>>
>
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