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drduncan
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9 hours ago, teaky said:

Does anyone have a view on Barry Norman's question regarding expanding lead?

The problem seems to occur when the lead is secured with PVA. I have heard of and seen reports of this happening especially when the lead was in small chunks. The acid in the PVA attacks the lead and causes it to corrode thus expanding and wreaking havoc with boilers.

 

Cheers,

 

David

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The cats eyes on Black Lion Crossing are carved from "plasticard", as is the Geoff Kent way.  They were also properly researched to represent the correct type, at the correct spacing for the period modelled.

 

As for the Barry Norman "lead" problem, he is aware of the problem with PVA glue as he mentions it in his letter. His lead was folded several times and stuck in with double sided tape. 

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5 minutes ago, t-b-g said:

As for the Barry Norman "lead" problem, he is aware of the problem with PVA glue as he mentions it in his letter. His lead was folded several times and stuck in with double sided tape. 

 

It makes me wonder if there was some reaction between the lead and the adhesive used on the DST. Finding out the chemical constituents forming the adhesive could be problematical as  I guess, it's only companies like 3M that may provide data sheets. 

I couldn't quite get my head around the photograph used to illustrate Mr. Normans letter. He said the lead had to be drilled to release it from the loco yet I couldn't see any evidence of drilling, only discolouration.

 

P

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I too have used epoxy without affecting the lead.  I can't imagine oxidisation is the problem since the lead on various parts of our house has simply become paler without expanding.  Barry's question intrigued me though since he clearly experienced some kind of damaging expansion and the MRJ photos show a sheet with some bubbling and a folded sheet which has changed to a pale brown colour.  It will be interesting to see if anyone comes up with the answer. 

 

Impurities in Barry's piece of lead, something it was coated with before he got it or a reaction with a material used in the model locomotive?  I didn't study chemistry beyond O-level so it is well outside my knowledge.

 

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But Barry's situation clearly stated there was no PVA glue involved.

I tend to agree with Porcy's hypothesis that it was something in the sticky tape formula producing the same effect as the known PVA problem.

I also wonder if in Barry's situation the lead was fully sealed in the side tanks, or whether there was an opening allowing air in. If that makes any difference, I wouldn't know.

 

Pete

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I've had a somewhat similar problem to Barry N.

 

I think the answer is probably something to do with galvanic corrosion.

Modern houses tend to be more or less draught proof and there's lots of moisture in the air.

 

I never realised how much humidity was in the railway room. Going through some of the cupboards I found photographs sticking together, and some older white metal kits and brass stuff suffering from Something similar.

 

Some old Airfix boxes showed signs of corrosion around the staples etc etc etc.

 

It was only when I bought a dehumidifier did I realise how 'wet' the atmosphere was.

 

It now has a permanent place in the railway room.

 

Had no further problems since.

Edited by BlackRat
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Bought a week ago but only just perused properly.

Am in awe of the 2 mm catenary, having tried years ago to scratch build catenary in 4 mm for my son's layout.

Geoff Kent's layout looks as good in the flesh as in the article. I have now seen it twice at shows and it is well worth looking out for.

And to my mild surprise I really liked the freelance layout. He achieves wonders in only seven feet, and though there is lots of detail it doesn't look crowded, while the overall effect is stunning and his attention to detail is impressive.

Am also impressed by the water tower and glad i don't need to build one.

What has happened to Mrs Trellis?

Jonathan

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6 hours ago, corneliuslundie said:

 

Geoff Kent's layout looks as good in the flesh as in the article. I have now seen it twice at shows and it is well worth looking out for.

 

 

Having been lucky enough to see it at Roy's last year, I reckon it looks even better in the flesh and that's not something that I've seen too often...

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On 02/03/2019 at 14:01, cctransuk said:

 

My reaction too - would that my painting was up to that standard !!

 

Regards,

John Isherwood.

 

I'm still struggling to see what's not acceptable or even better than acceptable about that paint finish. Maybe the red lining is a little variable in depth, but hey ... I'd be very, very pleased indeed with that.

 

 I loved Black Lion Crossing, fantastic layout and well described, but I'd have done something about the tilted verticals in that cover shot.

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