Just been having a browse through the May Railway Modeller, and in the feature on Woodfield Road, in that other scale not to be mentioned on a forum such as this, is an interesting comment on how he ballasted his track.
He refers to mention being made of Johnsons Kleer being used as a varnish, and as an adhesive. With the withdrawal / replacement / improvement of Kleer, and the silly prices the original does fetch on internet sales sites, he says he has used Astonish Flawless, which is available at one of the pound shops, and which he has found suitable for securing ballast.
He does not clarify if it can also be used as a varnish in the same way as Kleer.
hope this may be of use / interest.
One thing to note with klear etc, I have a 24 year old railway with pva attached ballast - no problems. Doing a stretch of relaying about 5 years ago I used Klear poured neat over the ballast and left to soak in. This worked fine and was easier than using pva but it is now in a state where ballast lifts (individual grains) when touched so does not appear to be that long-lasting.
Elmo
I also used the 'original' Johnson's Klear with Peco track, at the recommendation of lads with an EM gauge layout who have used it with great success. I've found, however, that it doesn't work long-term on my layout: I wonder if it could be partially due to the extra depth of ballast necessary with proprietary N gauge track? I used exactly the same product as they did.
I'm now using the more conventional method of diluted PVA, which I have found to be much more reliable at retaining the ballast as well as being much cheaper to use. Just be careful around point blades and switches!