Re: More on Metal Sundial Processes
Jack Aubert asked: A couple of questions... 1. Is it OK to leave the piece in the anodizing bath for a long period... I mean does it have to be removed when it's done or will it continue to cook and spoil the finish somehow. If you allow the anodic film to continue building it will eventually take on a lumpy 'orange peel' surface. 2. Since the easiest way to get DC without rigging up any electronics is to just hook up a 12 volt automobile battery, could one just a 12 volt automobile battery and leave the piece in longer? I don't have a handy source of 16 volt DC, and would have to either buy something ready-made or rig it up from parts. I've no experience of using a constant-voltage source so I can't really comment in detail but I suspect you may have problems. For the first few minutes of the process the voltage would fluctuate pretty wildly so it had to be 'chased' with the variable control to maintain 16 volts. We had the luxury of a continuously variable 0-20 volts 8amp AC/DC supply so this was easy. I'd just try it and see what happens. That's how I began. If you have an old 'open frame' 12V transformer it's fairly easy to add a few extra turns to put in series with the secondary winding to boost the voltage. A couple of other memories while I'm writing. The film is extremely hard and increases the rigidity of the workpiece markedly. If you want a curved workpiece then bend it before anodising. While it will resist abrasion, a sharp point can be forced through the film into the soft aluminium underneath. A piece of kitchen foil becomes very stiff and brittle when anodised. Try not to disturb the workpiece once anodising has begun. If electrolyte seeps into the joint with the connecting wire the joint itself will anodise and cut off the workpiece (the film is an insulator). The wire will then 'burn' at the liquid surface. Best Wishes T.
Re: More on Metal Sundial Processes
Tony et al., In Volume 2 (Mechanical) of Advanced Telescope Making Techniques, Selected Articles from the Maksutov Circulars, Edited by Alan Mackintosh*, Chapter 10, The Telescope Maker's Workshop, there is an article titled, Anodizing For The Amateur Telescope Maker by Maurice V. King. pp. (261-265.) There is a follow-up, Aluminum Finishing Experiences, by Gordon Rayner pp. (265-266,) which has notes made by Mr. Rayner after he had used the King instructions to guide his beginning efforts with the technique. Although they cover similar matter to Tony's postings, there may be some additional details of value for a tyro dialist. These articles have accompanying bibliographic, and sources-of-supplies information that could be particularly helpful to workers in the U.S.A.. - * Library of Congress Cataloging-in Publication Data: Advanced telescope making techniques. Includes index. Contents: v. 1. Optics v. 2. Mechanical I. Telescope, Reflecting. I. Mackintosh, Allan, 1909- QB88.A385 1986522'.286-18935 ISBN 0-943396-11-5 (v. 1) ISBN 0-943396-12-3 (v. 2) Willman-Bell, Inc., P.O. Box 35025 Richmond, VA 23235 Info Orders, 804-320-7016 Website at WWW.WILLBELL.COM Bill Maddux
Re: More on Metal Sundial Processes
Tony, Great stuff! Can you give any indication of how much currect is needed (per square inch of object?). Also, have you ever tried masking some areas of the film ( hour numbers) before the dying process, so that they come out a contrasting (or clear) colour? Cheers, John - Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
Re: More on Metal Sundial Processes
Can I just add a note of caution to Tony's note that concentrated caustic soda is really nasty stuff as well as the sulphuric acid. If you get a splash of conc caustic soda in your eye, don't bother to rush to the tap - by the time you get there it will have already gone !!! Have fun but BE CAREFUL and wear appropriate protective gloves AND GOGGLES Mike [EMAIL PROTECTED] 53.37N 3.02W Chester, UK
Re: More on Metal Sundial Processes
Roger Baily contributed: Great, informative note. I always wondered how these coloured oxide films were created. Thanks, I will try your techniques. Have you, or others on the list, had any experience using caustic to chemically etch aluminum? We used to make hydrogen to fill party ballons and make mini hydrogen bombs by reacting aluminum foil with a caustic solution (Draino or lye) in a pop bottle. I often thought that this process could be used to etch masked aluminum surfaces to produce the base plate for a horizontal dial. I never did reduce the idea to practice as the hydrogen ballons and bombs were more fun. Were you more successful? Roger and 'Watchers' Etching with caustic soda is an interesting stage in an easy form of multi-colour anodising - probably very relevant to dial making! Bill Maddux recently suggested etched aluminium dial plates to me. Come to think of it that is probably what jogged this current memory. Thanks Bill! Stages. 1. Produce the anodic film. 2. Dye and seal. 3. Stick on self-adhesive paper shapes. Numerals? Lines etc. 4. Spray with auto paint aerosol. 5. Just as the paint is almost dry (critical) pick off the gummed shapes. 6. Place in caustic soda which will etch away the exposed coloured areas. 7. Re-anodise and re-dye a different colour through the 'hole' OR 8. Polish the exposed aluminium on a polishing wheel. The surrounding anodic film is impervious to jewllers' rouge leaving mirror-bright lines/shapes on a coloured background. 9. I discovered (or re-discovered) this process (and several others) by experiment. Has anyone else trod a similar path? Tony Moss == \ ** ** \\ ** ** \\** *** *\\ ** ** *\\ ****** **\\ ***\\ Tony Moss, Lindisfarne Sundials *\\ 43, Windsor Gardens, Bedlington, ***\\Northumberland, England, NE22 5SY, **\\55° 07' 45 N1° 35' 38 W Tel/FAX +1670 823232 Mobile: 07970 208 540 Website: http://www.lindisun.demon.co.uk == The first choice for a Millennium Sundial. (every one Y2K compliant) Horizontal, Vertical, Declining, Analemmatic, Equatorial, Polar and Capuchin Sundials individually made in solid engraving brass. Professional-quality Dialling Scales, 'engine-divided' meridian layout instruments with software. Analemmatic dial plots - any size for any latitude. Graduation, re-cutting and restoration of scales. 'Lintique' patination of brass. ===
Re: More on Metal Sundial Processes
Warren Thom wrote: I have looked around the web for more information and found a caution of: Because of its porosity you do not get a satisfactory anodized finish on cast aluminium which has been machined. An as-cast aluminium surface will not have a lusterous finish when anodized. (looks poor) What might one do if they wanted to anodize the Schmoyer dial? It is aluminum cast, isn't it? Will it work on a cast surface that has been smoothed? What does it mean to be machined? I would think machined means to grind and mill the surface smooth. Have you found surfaces of aluminum (or is that aluminium - Al u MIN nee um) that have not worked well? In my limited experience of anodising aluminium castings, if you want clear, even 'bronze look-alike' I would have to agree. The few castings I anodised were always blotchy, even on dressed surfaces. I have no evidence to support my theory but I always thought it might be due to uneven dispersion of copper in the skin of the casting or just its irregular structure due to skin chilling. A partly dressed LM6 sandcasting dyed black took on an interesting silvery grey 'forged iron' look which we often used to good effect but other than that I would always select drawn or rolled material for anodising. I have found your steps very interesting. I have always wanted to find a good link of sun dialing to chemistry. That is how it started for me. I was tasked with finding interdisciplinary projects which would involve contributions from the teachers of chemistry, physics, art and workshop crafts. What could be better than anodising? Many sessions, many kids, much anodising and not a single incident. Best Wishes Tony == \ ** ** \\ ** ** \\** *** *\\ ** ** *\\ ****** **\\ ***\\ Tony Moss, Lindisfarne Sundials *\\ 43, Windsor Gardens, Bedlington, ***\\Northumberland, England, NE22 5SY, **\\55° 07' 45 N1° 35' 38 W Tel/FAX +1670 823232 Mobile: 07970 208 540 Website: http://www.lindisun.demon.co.uk == The first choice for a Millennium Sundial. (every one Y2K compliant) Horizontal, Vertical, Declining, Analemmatic, Equatorial, Polar and Capuchin Sundials individually made in solid engraving brass. Professional-quality Dialling Scales, 'engine-divided' meridian layout instruments with software. Analemmatic dial plots - any size for any latitude. Graduation, re-cutting and restoration of scales. 'Lintique' patination of brass. ===
Re: More on Metal Sundial Processes
Hi Tony, I have looked around the web for more information and found a caution of: Because of its porosity you do not get a satisfactory anodized finish on cast aluminium which has been machined. An as-cast aluminium surface will not have a lusterous finish when anodized. (looks poor) What might one do if they wanted to anodize the Schmoyer dial? It is aluminum cast, isn't it? Will it work on a cast surface that has been smoothed? What does it mean to be machined? I would think machined means to grind and mill the surface smooth. Have you found surfaces of aluminum (or is that aluminium - Al u MIN nee um) that have not worked well? I have found your steps very interesting. I have always wanted to find a good link of sun dialing to chemistry. Thanks Warren Thom Tony Moss wrote: Anodising Aluminium in the Home Workshop
Re: More on Metal Sundial Processes
Hi Tony, Great, informative note. I always wondered how these coloured oxide films were created. Thanks, I will try your techniques. Have you, or others on the list, had any experience using caustic to chemically etch aluminum? We used to make hydrogen to fill party ballons and make mini hydrogen bombs by reacting aluminum foil with a caustic solution (Draino or lye) in a pop bottle. I often thought that this process could be used to etch masked aluminum surfaces to produce the base plate for a horizontal dial. I never did reduce the idea to practice as the hydrogen ballons and bombs were more fun. Were you more successful? Roger Bailey N 51 W 115 )At 12:32 AM 11/11/99 +, Tony Moss wrote: Fellow Shadow Watchers Continuing my occasional series of practical approaches for metal sundials here is a distillation of my personal notes on anodising aluminium prepared over many years of practical experience. Aluminium has a normally dull and soft surface but anodising can transform this into beautiful multi colours with a weatherproof surface hard enough to resist all but the sharpest instruments. Interested? Then read on!
