If the white ink is in open bottles it's shelf life is somewhat reduced and should be in constant motion or shaken every couple of days. The latest generation of white ink can be remixed even after settling but will take some heavy agitation and shearing.

If your white ink is in a sealed vacuum packed bag the shelf life is greatly extended and should be shaken weekly. This is the preferred method since the ink is in it's own invironment and will not induce air when shaken.

The color ink is not as sensitive but still should be shaken from time to time.
Again closed bags will extent the life of both inks.

In both cases keeping the storage temperature should be under 70F or 21C.

 

Make sure your bottles are sealed tight. Store in temperatures of 60 to 75 degrees F. Shake the bottles slightly every other day. We have some people shaking the bottle gently and then turning it upside down and repeating every other day.

Harry
Equipment Zone

 

Excuse me, let me ask, so the ink temperature in the machine must still keep the 21 degrees C?
Thanks

 

I found a couple of these laboratory rollers on Ebay - I put a timer on the mains feed set to stir the inks for 5 minutes a few times each day.

 

Dupont, in their data sheet, recommends continuously rolling the white ink to extend the shelf line from 6 months to 1 year. I don't use enough ink yet to require the nice setup you have so I have the white ink bottles on a couple of rock tumblers.