tramcar trev
all manner of mechanical apparatus...
As I discussed a few posts back I have to etch some small plaques. I have some iron on film for photographic processing but it has a limited shelf life and I think it may be way beyond its shelf life so I used the iron on laser printer film.... The makers claim that .01mm lines are possible so I thought as the smallest line width I was working with is .25mm I should be ok. The brass sheet needs to be scrupulously clean, don’t use steel wool; rather a plastic scourer and maybe Ajax though I used “Gumption”. This gets the surface really clean and polished so you will be able to read the lettering on the background of duller etched brass.
Printing the film went well with a little experimenting. The detail I wanted is well within the capability of the printer but large expanses of black around the object to be etched caused some problems, the printer didn’t like to print them on the film but it printed on paper quite well. Eventually by tweaking the printer settings it came out as well as I hoped... The film is positive i.e. what you see is what is NOT ETCHED but as you have to print on the side of the film that is against the brass you have to print mirror image so that when viewed through the film you see what you will get. Mask out areas you don’t want etched with clear packing tape, it resists the heat of the etching process.
Application was a bit unfocused. I then used a sheet of plain paper between the iron and the film to stop minute movements. The iron temperature is critical but not that critical, I set mine halfway between “synthetic” and “wool”, as recommended. Iron the film on gently, let the heat and weight of the iron do the job, too much pressure can distort the image. Then you have to “quench” the sheet in cool water, I think the quick contraction helps release the film from the ironed on image.
Peel the film off and the next step as recommended is to go over the image with sticky tape. This cleans up the “furriness” around the detail and you can see quite a bit of fine blue lines coming away as well as the centres of filled letters which otherwise would not etch.
The etching itself I eventually did with ammonium persulphate. Mix it with demineralised hot water, make the water hot by putting it in a microwave in a plastic jug, I boiled mine and mixed it while it was very hot... While that was going on I had boiled the electric kettle as I needed to keep the etchant hot. I used a plastic esky as a “Baine Marie” to keep things hot. Do it outside with plenty of natural ventilation. Rubber gloves and goggles are a very good idea for mixing and using Ammonium Persulphate. The etching process took about 20 minutes and gave a depth of around 10 thou. Far quicker and cleaner than ferric chloride.... During etching I occasionally lifted the brass out of the tank and agitated the surface with a 1/2” paint brush, this removes fine specks of the mask and any remnants of adhesive from the sticky tape that would show as shiny spots on the finished job.
As I don’t have a guillotine (I must try and source a small one for cutting brass sheet) I cut the plaques from the sheet using an “Olfa Plastics Cutter” it has a very sharp hook type blade that was good for scoring half way through then its just a matter of folding on the scored line and the plaques come away cleanly...
The printed on mask is easiest cleaned off with some acetone rather than scrubbing with steel wool, (as recommended) steel wool will tend to polish the etched areas that you want to remain etched to imitate cast bronze. A couple of coats of automotive clear coat work well to keep it weatherproof and looking readable. Something I did not do with the earlier etched plaques.
The Photos show the finished job. I’m really pleased with the result the small print is quite legible despite being 1mm high and the “Fleur de Lis” came out well. I did want to use a “Rising Sun” and made the mistake of seeking permission, lets just say that after trying to “get through” to a bureaucrat trained to think in a 10Hz bandwidth I went with the Fleur de Lis..... Next time I`ll buy a miniature “Rising Sun” from the War Memorial Gift shop and use that....
Despite my complete success with this job I`m going to make my Bandstand in “Federation” style timber rather than Victorian cast iron lace, to etch that much brass would require a lot of Ammonium persulphate. Etching like this to a decent depth uses a lot of etchant, the tank holds ½ litre and was exhausted after etching these plaques... I used about 2kg of ferric chloride to etch the trolley ears. I do have to make “Tram Stop” signs and they will be etched with an enamel infill....
Printing the film went well with a little experimenting. The detail I wanted is well within the capability of the printer but large expanses of black around the object to be etched caused some problems, the printer didn’t like to print them on the film but it printed on paper quite well. Eventually by tweaking the printer settings it came out as well as I hoped... The film is positive i.e. what you see is what is NOT ETCHED but as you have to print on the side of the film that is against the brass you have to print mirror image so that when viewed through the film you see what you will get. Mask out areas you don’t want etched with clear packing tape, it resists the heat of the etching process.
Application was a bit unfocused. I then used a sheet of plain paper between the iron and the film to stop minute movements. The iron temperature is critical but not that critical, I set mine halfway between “synthetic” and “wool”, as recommended. Iron the film on gently, let the heat and weight of the iron do the job, too much pressure can distort the image. Then you have to “quench” the sheet in cool water, I think the quick contraction helps release the film from the ironed on image.
Peel the film off and the next step as recommended is to go over the image with sticky tape. This cleans up the “furriness” around the detail and you can see quite a bit of fine blue lines coming away as well as the centres of filled letters which otherwise would not etch.
The etching itself I eventually did with ammonium persulphate. Mix it with demineralised hot water, make the water hot by putting it in a microwave in a plastic jug, I boiled mine and mixed it while it was very hot... While that was going on I had boiled the electric kettle as I needed to keep the etchant hot. I used a plastic esky as a “Baine Marie” to keep things hot. Do it outside with plenty of natural ventilation. Rubber gloves and goggles are a very good idea for mixing and using Ammonium Persulphate. The etching process took about 20 minutes and gave a depth of around 10 thou. Far quicker and cleaner than ferric chloride.... During etching I occasionally lifted the brass out of the tank and agitated the surface with a 1/2” paint brush, this removes fine specks of the mask and any remnants of adhesive from the sticky tape that would show as shiny spots on the finished job.
As I don’t have a guillotine (I must try and source a small one for cutting brass sheet) I cut the plaques from the sheet using an “Olfa Plastics Cutter” it has a very sharp hook type blade that was good for scoring half way through then its just a matter of folding on the scored line and the plaques come away cleanly...
The printed on mask is easiest cleaned off with some acetone rather than scrubbing with steel wool, (as recommended) steel wool will tend to polish the etched areas that you want to remain etched to imitate cast bronze. A couple of coats of automotive clear coat work well to keep it weatherproof and looking readable. Something I did not do with the earlier etched plaques.
The Photos show the finished job. I’m really pleased with the result the small print is quite legible despite being 1mm high and the “Fleur de Lis” came out well. I did want to use a “Rising Sun” and made the mistake of seeking permission, lets just say that after trying to “get through” to a bureaucrat trained to think in a 10Hz bandwidth I went with the Fleur de Lis..... Next time I`ll buy a miniature “Rising Sun” from the War Memorial Gift shop and use that....
Despite my complete success with this job I`m going to make my Bandstand in “Federation” style timber rather than Victorian cast iron lace, to etch that much brass would require a lot of Ammonium persulphate. Etching like this to a decent depth uses a lot of etchant, the tank holds ½ litre and was exhausted after etching these plaques... I used about 2kg of ferric chloride to etch the trolley ears. I do have to make “Tram Stop” signs and they will be etched with an enamel infill....
