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photosensitized boards have a "use by" date ???

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Simon:
I bought some presensitized double sided board from Farnell and it actually has a use by date on it ??? What ? we are talking photographic chemical right ? it is supposed to last years. I have a 2' square sheet that I bought off RS a year ago and I'm still using lumps off it as and when required yes the farnell stuff has 3 month date on it.

Ideas anyone ?

Zyvek:

--- Quote from: Simon on December 28, 2010, 05:09:25 pm ---I bought some presensitized double sided board from Farnell and it actually has a use by date on it ??? What ? we are talking photographic chemical right ? it is supposed to last years. I have a 2' square sheet that I bought off RS a year ago and I'm still using lumps off it as and when required yes the farnell stuff has 3 month date on it.

Ideas anyone ?

--- End quote ---

Simon, if they are anything like the darkroom chemicals I used to use, just keep them in an airtight container and you can usually exceed the use by date with any major problems. Throw a silica gel pack in to reduce moisture.

Cheers.

Simon:
well having a protective plastic sheet over the board pretty much makes them airtight to my mind. it is the first time I hear of a use by date, to be honest I call "bull shit" on it

Zero999:
They're just being cautious.

It makes sense that the photo-resist will degrade over time. I think the temperature and background radiation will be the most significant factors: I think ionising radiation will cause the photo-resist to become exposed and it's likely to be more sensitive at higher temperatures.

I'd say the date is more for them than the consumer - I don't think you'd like it if they sold you some 10 year old board which gave poor results.

Zyvek:

--- Quote from: Simon on December 28, 2010, 06:45:07 pm ---well having a protective plastic sheet over the board pretty much makes them airtight to my mind. it is the first time I hear of a use by date, to be honest I call "bull shit" on it

--- End quote ---

Agreed.  Just a way to ensure more business!  It's not like were talking about food!  If it's the photo sensitivity, keeping them in dark storage will also help. As they age it might need a longer exposure, but unless you pull the plastic off and leave them direct in sunlight I'd imagine they are still usable.

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