I had occasion to chat with the legendary Tim at Fresh Roast today. Seems my old (less than one year) Fresh Roast developed a crack in the bakelite collar around the bottom of the roasting chamber that seals it to the base. Since it's bonded to the glass, it won't drop off, but on one side the crack goes all the way through from top to bottom and could constitute a blowby leak. I asked Tim if he could suggest any way to seal it at the operating temperatures of the unit. I have this thing about wanting to salvage stuff like this rather than replace it. Tim suggested using an epoxy, but didn't know if there were any with a high enough temperature rating to survive. He though DAP might make one, but wasn't sure. He volunteered to replace the chamber, but I told him I'd call him back if I failed to seal it. Somehow, the idea of replacing the chamber every year is not very appealing. Since I haven't seen this brought up as a Fresh Roast problem on the list since I joined it last year, this unit may be a straggler. That would be more comforting, actually, since a replacement would then be more likely a long term solution (infant mortality, you know). If anybody has some suggestions for a high temp (~400-450F) epoxy seal, I'd appreciate hearing about it. Carl T. homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast
From: "Carl Thomas" Subject: +Tim Strikes Again! Date: Wed, 23 Jan 2002 00:09:14 -0500 <Snip> I tried to search for epoxy resin with highest temperature resistance before, but the best was still well under that range. There are some other resins that can sustain higher temperatures for limited duration of exposure. They (including epoxy) lose strength as heat exposure prolongs, and the deterioration is cumulative. It's not just below or above specified temperature limit kind of thing. -- Ryuji Suzuki "I can't believe I'm here. People always say that I'm a long way from normal." (Bob Dylan, Normal, Illinois, 13 February 1999) homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast
Don't use epoxy, use a hi-temp silicone gasket material like versachem's hitemp red. Good to like 550. I use it all the time in the heating sections of my roaster hacks. Available at auto parts stores. Ted *********** REPLY SEPARATOR *********** On 1/23/2002 at 12:09 AM Carl Thomas wrote: <Snip> base. <Snip> didn't <Snip> Somehow, <Snip> I <Snip> I'd <Snip> homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast
Marine-Tex is used to patch marine engine blocks (among thousands of other things) so it would withstand the changes in temp, but I am not sure it is suitable for contact with food. If the crack is not touching where the beans are, and you run several roasts either without beans or with ones you throw away, you would probably be able to use Marine-Tex to patch it and then outgas the repair completely before using it for actual roasting. High temp silicone repair caulk that is rated foodsafe would also be a good possibility.
Thanks to the folks who responded. I think I may have some of the gasket seal. The cracks in the ring are outside the roasting chamber where it fits into and sets on the base, so exposure to the beans should be no problem if I only use it at the top of the crack outside the base. The crack isn't that big and I have yet to detect any significant blowby, but yeh, verily an ounce of prevention and all that. I also didn't think to ask Tim if he knew what they used to seal the glass and perforated plate to the ring to begin with. It looks like a dark organic. Oh, well. I'll give the gasket sealer a try and if that fails, Tim volunteered a new one chamber. But, gee, I just hate to give up on the old one. Comes from my younger days with old cars. Thanks again. Carl T. homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast