Barry, Leave em alone it won't hurt and I doubt whether you'd notice the difference. Regards IP "Life should NOT be a journey to the grave with the intention of = arriving safely in an attractive and well preserved body, but rather to skid in sideways, Champagne in one hand - strawberries in the other,=20 body thoroughly used up, totally worn out and screaming WOO HOO - What a Ride!"=20 =20 "Never drive faster than your gaurdian angel can fly" =20 Priest & Sons Model Engineers http://www.kinvermes.pwp.blueyonder.co.uk/p1.htm -----Original Message----- From: modeleng-bounce@xxxxxxxxxxxxx = [mailto:modeleng-bounce@xxxxxxxxxxxxx] On Behalf Of Barrie Purslow Sent: 12 September 2005 12:21 To: Model Engineering List Subject: [modeleng] Boiler blues I am restoring a 5" Duchess the boiler of which is in generally good condition. However the flue tubes, which are about 15/16 ins. I.D., are coated internally with a layer of hard, black carbon. I have given it = the usual flue brush treatment which produced clouds of black dust but a = hard layer about 1/64 ins. thick remains. I have tried fitting the flue brush into an electric drill and giving the tubes a few minutes of rotary = action to little effect. I am wary about trying anything more aggressive as I = have heard quotes of over =A32000 for a replacement boiler. Any ideas anyone? Barrie Purslow Warrington UK=20 MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to,=20 modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the = subject line. 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.