Colour change .

Sorry, it does seem I lost a "square root" somewhere in my calculation, I'm more rusty than I'd thought. 

I'm going back to the late 1960's when I was doing chemistry. Took me some thought as well. As I said, bottom line re PVA is to check the SDS and make sure the pH is acceptable, or use the "neutral" stuff. Looking at the reaction(s) between copper and acetic acid I have a feeling that a current going through the copper will accelerate the reaction. Some care in ballasting will make sure the PVA doesn't touch the rails.

John, apologfies for the side-track on PVA and verdigris. I see painting the ballast has been recommended. I wouldn't, if you have some lighter grey ballast left paint the dark with some PVA/alcohol  and sprinkle some of the light on top. Tedious, but it minimizes the use of the ballast.

Nigel

Maybe the chips made a difference Colin …………………… :roll:

I'm no chemist Nigel but to me, SDS is a type of electric drill - an excellent type to boot !!   :roll: :cheers

Safety Data Sheet.  :roll: Used to be called Material Safety Data Sheet (MSDS). Has to give the characteristics of the active material, plus handling, safety data,….

SDS chemically commonly refers to sodium dodecyl sulfate, also known as SLS. Everybody knows that, you use it's every day in one form or another. Check your bottle of dishwasher luquid.


Nigel

The name Fatima Whitbread always makes me chuckle, many years ago a friend went to a prestigious 'do' in London, where with others he received an award for his charity work, needless to say he got rather 'tired and emotional' in the bar afterwards.

Being helped back to his room, in the lift, he stood at the back and his attention was drawn by a very shapley derrier in a slinky skirt, so he gave it a friendly squeeze. Totally out of character…

He woke up 5 floors higher, sitting on the floor.

Of all the women in the world to choose to start touching up, Fatima Whitbread would be very low on my list, I assure you. He wore his black eye for nearly 3 weeks!

D

I was worried for a minute, and then realised Doug had posted in the wrong thread...