Re: Making Metal Sundials II
http://www.techniks.com/press-n-peel.html Price there is $30 for 20 sheets. Gordon At 11:59 AM 11/22/1999 , Tony Moss wrote: Al Schoepp contributed: It sounds similar to the film described above. Tell me more. It comes in 8.5 X 11 sheets and seems to cost about $1.50 - $2.00 per sheet, depending on where you buy it. Rather than atempting to explain it following are 2 webpages, the Techniks page is the manufacturer of the film. The other site has some info on it and also sells the stuff in the UK. http://www.cibs.co.uk/etch/ Gordon Uber [EMAIL PROTECTED] San Diego, California USA Webmaster: Clocks and Time: http://www.ubr.com/clocks
Re: Making Metal Sundials II
Al Schoepp contributed: It sounds similar to the film described above. Tell me more. It comes in 8.5 X 11 sheets and seems to cost about $1.50 - $2.00 per sheet, depending on where you buy it. Rather than atempting to explain it following are 2 webpages, the Techniks page is the manufacturer of the film. The other site has some info on it and also sells the stuff in the UK. http://www.cibs.co.uk/etch/ This is an exciting find Al. Anyone who wants to know more about commercial etching will probably find the information and the necessary supplies here BUT £6.+ per A4 sheet of 'Press-n-peel' !!! (assuming VAT payable - it doesn't say) compared to $1.50 - $2.00. in US. Ripoff Britain! - here too! For anyone interested in beginning photoetching it's well worth having a look at the webpage. On reflection, and at those prices, I may just stick with my home-made, low-budget, tried-and-tested processes but for someone just beginning this may be the way to go. Thanks again Al, Tony
Re: Making Metal Sundials II
John Davis contributed: This is real cookery! As an alternative to etching face down in a flat dish, it is simple to use a vertical tank as supplied for etching PC boards. These are tall and very thin - about 1.5 cm wide, and big enough to take the plate that is being etched. Easy to make with two sheets of perspex spaced apart and sealed with silicone. Agitation is provided by a steady stream of air supplied to a perforated tube in the bottom of the tank by an aquarium pump. A heater, again of the sort to stop your tropical fish freezing, gets the ferric chloride to a usable 40C. The key is to get a good quality photoresist that doesn't fail - the aerosol type has a very limited shelf-life, I've found. I'm ever ready to yield to the voice of experience as my own is limited to several hundred printed circuits and a few dozen deep etched sundials over the years. For the benefit of the List members who might consider trying the process, I have a few observations which beg a number of questions, There is a world of difference between cloisonne-depth etching - typically 0.3 - 0.5mm - and printed circuit making where something like .05mm has to be etched away and the process stops on reaching the substrate. The metallic layer is so thin that 'undercutting' is hardly a consideration and etch time is in minutes rather than hours. I'm sure John is quite right in championing the efficiency of the 'on edge' type of bubble etch tank for printed circuits with a stream of bubbles to provide not just mechanical agitation but aeration which speeds the process. Commercial processes go further (or did) in directing jets of hot ferric chloride carrying entrapped air against vertical circuit boards. They probably cut them out with lasers these days for all I know! In any event, the process is quick and the etching is shallow. I've not tried deep etching 'one edge' so I can't quote from experience but I suspect that there might be problems with undercutting on the upper edge of horizontal features unless the plate is turned regularly. When etching is prolonged and agitation vigorous there is a real chance of the resist breaking down and peeling away. Surface preparation is important here. The grade of abrasive must be coarse enough to provide a 'key' for the coating to grip but not so coarse as to make finishing problems. Mirror finished metal is a disaster! As the resist is removed by an alkaline 'developer' - very similar, if not identical to, dishwashing machine powder (MUCH cheaper!) - I employ an acidic pre-coating wash by using ordinary kitchen vinegar as the 'lubricant' for my 'wet dry' abrasive paper followed by a thorough wash in warm water and drying with clean paper towel to remove any possibility of alkaline contamination. Then there is the consideration of volume of etching fluid. With 'on edge' tank you must fill it each time if you want to use fresh etchant for consistent results and that will increase your costs. Horizontal dish etching requires just enough to immerse the lower face of the plate. I have my dish rocking machine set to give a shallow tilt to the dish every six seconds. Plastic 'cat litter' trays cost buttons and are ideal for this. The shallow tilt gently changes the solution in contact with the metal carrying away slurry but not attacking the delicate resist by any mechanical action - quite the reverse of printed circuit making. As a result undercutting is kept to a minimum until full depth has been achieved. JPEG of a closeup of a sample of deep etching in due course. I remain to be convinced but even then I'll probably stick with what works for me out of laziness if nothing else.. The dinosaur saddles I make are the finest available and I only charge one handful of tyrranosaur teeth for them. :-) Best Wishes Tony (Flintstone) Moss P.S. This must be deadly boring for 'mainstream' sundiallers so I think it's time to hibernate for a while.
Re: Making Metal Sundials II
This is real cookery! As an alternative to etching face down in a flat dish, it is simple to use a vertical tank as supplied for etching PC boards. These are tall and very thin - about 1.5 cm wide, and big enough to take the plate that is being etched. Easy to make with two sheets of perspex spaced apart and sealed with silicone. Agitation is provided by a steady stream of air supplied to a perforated tube in the bottom of the tank by an aquarium pump. A heater, again of the sort to stop your tropical fish freezing, gets the ferric chloride to a usable 40C. The key is to get a good quality photoresist that doesn't fail - the aerosol type has a very limited shelf-life, I've found. Cheers, John -- Dr J R Davis Flowton, UK 52.08N, 1.043E email: [EMAIL PROTECTED]
Making Metal Sundials II
Fellow Shadow Watchers, While recently making a reproduction of a 10 octagonal Victorian??? dial (the client wishes to replace the flimsy original with a more robust version in phosphor bronze) I've taken JPEGs at various stages of the etching process. The first three show details of a simple 'etching machine' I made some years ago to eliminate the labour of dish rocking over periods of several hours. There are many variables in the 'cloisonne depth' etching necessary for sundials. For phosphor bronze hot fresh Ferric Chloride + agitation face down in a dish will etch deeply in 2/3 hours.*Cold fresh Ferric Chloride + agitation takes 7-9 hours. Old 'used' Ferric needs heat and prolonged agitation although this can result in undercutting and breakdown of the 'resist' film. There's no immediate substitute for experienced 'know how' I'm afraid. I've been etching since the 1960s and still encounter surprises. *Etching 'face up' is slowed down or stopped by the slurry removed from the metal settling back into the etched lines. Etching 'face down' without agitation can suffer from trapped air bubbles causing blind spots on the work. Plates MUST be supported above the base of the dish by about 5mm to allow free flow of liquid and prevent damage to the resist coating. I use small pieces of acrylic sheet with a slot wide enough to slip onto the plate set 5mm from one edge. The required strength is approximately 500grams of ferric chloride per litre of water. Supplies of chemicals and resists can be obtained from many electronics hobby shops where it is used for making printed circuits. SAFETY NOTES Ferric Chloride doesn't evolve fumes when etching BUT it should not be left uncovered near metallic items which will be attacked by vapour over time. It is an irritant so skin and eyes MUST be protected and quite small amounts are potentially fatal if swallowed. The exhausted fluid and the slurry it contains MUST NOT be disposed of by normal drainage/sewerage or any method which will endanger, people, animals, crops or water supplies. You should consult your local regulations for its safe disposal. If you are already on my sub-list to receive 'Making Metal Sundials' JPEGs I will be sending these out in a few days time. If you wish to be removed from the sub-list please let me know asap. If you would like to be added to this distribution list let me know. Best Wishes Tony Moss In response to popular demand I'm NOT including my gallumphing auto-signature - for a while.
