by Dinesh » Wed Dec 08, 2010 5:53 pm
Tony wrote:Great to see you on the forum Dinesh! Welcome
Thanks!
Tony wrote:Do you ever recharge your IPA? How do you know when the IPA concentration is getting too low? Or do you simply swap out IPA on a timetable or X amount of plates?
When the holograms get weak! I don't do a lot of display stuff anymore. Mostly, I'm making notch filters now. We have a spectrophotometer to test the filters and I notice that the efficiency drops after 4 or 5 plates, so I generally renew.
I "recharge" the plates by using the the higher concentration alcohol to make the lower concentration alcohol and the used 100% alcohol to make fresh lower concentration alcohol. This way, there's very little waste, except at the low end.
So, I start with 50%, 75%, 100% cold and 100% hot. After (let's say) 5 plates I throw away the 50%, calculate how much extra water I need to convert the 75% to 50% (taking into account that a certain amount of water gets transferred along with the plate as it goes from water to the first 50% bath - I usually figure it's about 10% weaker due to the water transfer), do the same for the 100% cold to the 75% and transfer the (old) hot 100% to the (cold) 100% tray. Now I refill the hot 100% from the alcohol tank. At the end of the day, I get rid of the 50 and 75% and transfer both the hot and cold 100% to a separate container because they're probably a hair under 100%. The next day, I use this separate container to make the 50% and 75% and use pristine alcohol, from the tank to make the hot and cold 100%.
[quote="Tony"]Great to see you on the forum Dinesh! Welcome[/quote]
Thanks!
[quote="Tony"]Do you ever recharge your IPA? How do you know when the IPA concentration is getting too low? Or do you simply swap out IPA on a timetable or X amount of plates?[/quote]
When the holograms get weak! I don't do a lot of display stuff anymore. Mostly, I'm making notch filters now. We have a spectrophotometer to test the filters and I notice that the efficiency drops after 4 or 5 plates, so I generally renew.
I "recharge" the plates by using the the higher concentration alcohol to make the lower concentration alcohol and the used 100% alcohol to make fresh lower concentration alcohol. This way, there's very little waste, except at the low end.
So, I start with 50%, 75%, 100% cold and 100% hot. After (let's say) 5 plates I throw away the 50%, calculate how much extra water I need to convert the 75% to 50% (taking into account that a certain amount of water gets transferred along with the plate as it goes from water to the first 50% bath - I usually figure it's about 10% weaker due to the water transfer), do the same for the 100% cold to the 75% and transfer the (old) hot 100% to the (cold) 100% tray. Now I refill the hot 100% from the alcohol tank. At the end of the day, I get rid of the 50 and 75% and transfer both the hot and cold 100% to a separate container because they're probably a hair under 100%. The next day, I use this separate container to make the 50% and 75% and use pristine alcohol, from the tank to make the hot and cold 100%.