At 02:56 PM 6/16/06 +0100, you wrote: >With a full sized loco, >Hope this helps Dave, Yes, I understand how boilers of different materials are made (don't I Alan) but I didn't realize the subject had turned to full size locos. Perhaps the reason I hadn't heard of this problem is because over here we have very few steam railways and even so composite (steel & copper) boilers disappeared for the most part well over 100 years ago. For better or worse I've never heard it mentioned as a problem in US live steam circles, but in general I'd prefer to have my firebox door closed. Regards, Harry MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.