Well, in the end I gave up waiting for the goo.
A full four days after I poured the silicone mix into the mould it was still soft and tacky. (It should be solid rubber after 24hrs!)
So call me impatient, if you like, but I've decided to cut my losses and I spent a miserable hour last night scooping it out and laboriously cleaning up the masters to have a second go.
I've made up another RTV mix and this time I've gone to the other extreme and I fully expect this lot of silicone will be cured in jig time.
Most of the difficulties, as I explained in a previous post, are because I am attempting to mix very small amounts at a time as I am testing each of the master parts for the ballast wagon kit as I go along.
Once they're all proved, and the prototype has gone together, I'll be able to make a complete set of 'production' moulds in one go. For that I'll be measuring out sensible amounts of the catalyst, such as 5g, instead of silly wee dribbles like 0.5g which have caused me such grief over the last week.