Thursday, 29 April 2010

Ever expanding PVA

This is from a still-born project for a Class 59/2 in P4 using a Life Like Proto 1000 PA-1 loco as a basis to provide a powerful all wheel drive model which could handle the sort of loads which the real locos could. However, two things have put pay to this.

Firstly the article on the latest ModelRail on rebuilding a 59 using Bachmann's 66 chassis as basis by one well known member of RMweb and secondly a problem with PVA...

As you can see it has expanded over the last three years and distorted the chassis frame. This problem is well documented in the letters page of Model Railway Journal but I filled the fuel tank with 'Liquid Lead' secured with diluted PVA some time before this first appeared. If I recall correctly the PVA reacts in someway with the lead causing the expansion. Here it's ruined one chassis frame but it must be heart-breaking to see one of your kitbuilt locos ruined by this. So I'm back to old methods using scrap lead flashing and Araldite!

All is not lost though, the remaining parts of the Class 59 will see reuse in the future as I would love a decent National Power Class 59 after spending hours with my dad watching them working on coal trains to and from Drax Power Station. The mechanical parts salvaged from the loco will see use much sooner - all will soon be revealed!


  1. Hi James,
    Thanks for passing on this extremely valuable information. I was considering using PVA/lead weight on a project, but thanks to your timely warning I'll be using strips/epoxy instead.

    Very interesting blog, keep up the regular posts!

    Kind regards ...

  2. It was my pleasure!

    I knew of the problems but had forgotten I'd used the combination here until yesterday!

    The liquid lead will be used up though; under open wagons which will be modelled running empty fixed using cheap liquid superglue.

    By the way - for cheap lead befriend a builder! I get mine from a friend of my parents' - they're just off cuts but keep me going for ages. He can't believe that model shops will charge a few pounds for a 6" square!


  3. Thanks for that James. I have been under the impression that PVA is the wonder glue for many applications. But this is based on experiences some 25 years ago when I was last modelling.

    I do enjoy catching up with your blog.