I bought a sample set of ply sleepers and crossing timbers from Exactoscale recently and thought I'd compare them to the C&L plastic ones I'm already familiar with. Appearance-wise I think the ply sleepers are far superior (despite what I've heard some people say to the contrary - the wood grain may not be perfectly to scale, but then it's sometimes illusion not exact scale that is the key to things looking right in model form). However, in terms of the strength of the bond between sleepers and the C&L platsic chairs, the C&L platsic sleepers are hands down winners. I did a little test with a plastic sleeper, untreated ply sleeper, and a ply sleeper that had been pre-coloured using a wash of thinned Enamel paints, using Butanone to atach two chairs to each. After 12 hours or so I attacked each one with a pair of tweezers, to see how much pressure was needed before each gave way. The chairs attached to the coloured ply sleepers gave way first, with fairly little pressure required to seperate the chairs cleanly from the sleeper. The untreated ply was next, with a little more pressure required to acheive the same result. The platsic sleeper was the clear winner - no amount of pressure could seperate the chair and sleeper - in the end the chair itself broke.
Now obviously this is a fairly limited test. I haven't tried other types of solvent/glue and I haven't taken into account what sort of forces are ever actually likely to be exerted on track in the normal operational life of a model. However, it does highlight the fact that the bond between ply sleepers and platsic chairs is not all that great, and this concerns me. I'm now not sure what to do. I'd be much happier with the strength of the plastic sleepers, but much prefer the appearance of the ply ones. Any advice anyone??