Electroless Nickel Questions

[XK120DHC]

Going to mix Five Pints of the Caswell EN and I have a few questions.
The brass part to be plated is right at 40 Sq In. The Plating Manual says to "Only add enough replenisher to bring the credits up to 100%" and suggests replenishment every ten minutes (another sentence says five minutes).. Okay, got that..
Plating a 40 Sq In part for 60 minutes will "consume" 2400 Credits. If I plate for ten minutes, I will consume 400 Credits, Replenish with .25 oz Part A and .5 oz Part C adds back 450 Credits putting me 50 credits "over" the 100% at every replenish.
Question #1. Can I plate for 11min 15 seconds instead? This figures out to consume 450 credits. I'll need to do five of these sessions with the last session being 3 minutes 55 seconds (this will start the next plating session at 1640 credits, 380 credits above the minimum of 1260) Am I being overly critical (anal) with respect to total credits and times?
Question #2. Should the part be removed during the replenishment process? Or is is okay to leave the part "cookin'"?
Question #3. After I mix my primary bath, can I go ahead and mix the total remaining four ounces of Part A with all eight ounces of Part C to make the Replenisher? Or just premix the two parts in an amount that will be used during one plating session?
Lastly, Question #4. What is the approximate "shelf life" of the primary EN Plating solution?
Any and all help appreciated.
Thanks.

[CarWiz]

1. Make your plating times based on the thickness of the plate required for your needs. I wouldn't worry about seconds. THEN calculate the credits necessary for the part(s). Plating thickness will depend on the use of the part. Too thin and it will wear off with use and/or provide little corrosion resistance.

2. Leave the part in for the duration of the plating cycle. Add the mixed replenisher a little at a time throughout the cycle.

3. Mix only what you'll use for the plating session.

4. I've had a batch sit idle for 4-5 months and it still performed well. I've had unmixed chemicals for over a year and they still plate perfectly. (Parts A, B & C)

Caswell indicates a bath can be used for about 10 sessions. I've gone quite a bit more with good results. The accuracy of your credits plays a big role on how long the bath lasts. The EN process is more tolerant with too much replenisher than it is being low. Also, how you care for the bath by not dragging other compounds into the batch makes a huge difference. Zinc, rust or cleaners/degreasers can ruin a bath in a hurry. The mixed bath is good until it starts to cloud. Once the bath becomes clouded, it's plating effectiveness drops sharply. (More than 50%) This is because of the formation of other compounds in the bath. The cloudiness is a normal reaction from using the electroless process. When it occurs, use the disposal process for the old batch then mix a new new batch.

[XK120DHC]

CarWix;
I appreciate the reply and info.. Thanks.
I didn't know how "critical" the "plating period" times needed to be, given a 40 Square Inch part and an hour long plating session time, not to mention "adding back" more "credits" than is consumed (by 10) after each "period".
I fully understand about drag-in/outs in plating baths.. I try to avoid it as much as possible.
After I plate this bulb holder, I have no immediate plans to EN anything else, so the bath may very well sit "for a while".. That said, I may find a dozen uses for the EN and have to buy another kit ;-}
I really appreciate the info on what the EN looks like when depleted.. I do mostly Zinc and a cloudy bath is no big deal.. I'd would have never thought that about the EN.
Thanks, again. Your reply was a HUGE help.