Hi everybody. I have always patinated on bronze, now i am tryin to do it on a 1mm copper sheet. Well, the sheets i am using are made for etchings, and they came protected with a plastic, i take it out, sand the sheet and wash it with water. Then i let it dry, and start the process, like i do with bronze. Well after i get the patina i am accostumed to wash and dry rubbing it with a clothe, before the lac and wax.
The problem with copper sheets, is that when i wash and rub them, a big part of the patina is gone,thing that doesn't happen to me with bronze.
. Shouldn't I rub it with the clothe before the lac and wax, and, if then, would that patina be stable and well set and preserved.
Maybe i am not sanding it the right way?
Should I apply an etcher after sand it and before the patina?
The patinas i am working are all hot patinas with torch.
Any Suggestion?
A lot of thanks.
To the forum, First thing you have to understand is the patina will react differently on alloys other than bronze. Second thing is that a patina for bronze may or may not hold as well on copper as it does on bronze. Matter of fact patinas are more delicate on the copper than on bronze. You didn't say if it was a hot or cold patina, hot patinas generally have better holding power no matter what material rather than their cold counterparts.
And yes you are correct in thinking that you may have to adjust your procedures in the application and finishing. After application of the patina and the rinsing instead of rubbing, pat the surface dry or gently heat the surface with a hair dryer to dry the piece.
Are you cleaning the surface after the sanding and removing all the residue from the sanding. Other then rubbing for high, low lights are you using a base patina or just a single coat.
Are you sure that you have removed all the plastic coating from the plates?
Whether it is bronze, copper, brass, or ferrous material each metal will have a slightly different process of cleaning, application, setting and sealing.
Most books on patination of bronzes or general metals will tell you that the patination layer or layers are the most delicate if the surface isn't cleaned and the patina applied properly and then sealed.
As You know patination is more of an art than science, Patience, is the number one thing you have to have. And that you may not get the same results twice!.
Thank you Glen for you quick answer. I was reediting my post while you were answering me, telling that the patinas, are hot. The last plate, the one which most patina i dragged from with the clothe, I was playing with , a cupric nitrate and a bit of liver sulfur patina, and another ferric nitrate patina, just playing with both on the sheet. About removing the plastic coat, yes i am sure i do remove it well. But not washing and rubbing after sand it, and to dry them finally with the hair dryier, sounds pretty good, i am triying on it. What about applying a semiliquid etcher before starting?, just after sand it.
Many thanks again
I have never heard or that other than to do a surface or background design to underlay the patina. You do what some tooth for the patina to grab to.
I don't know if you are using steel wool as one of your final steps in clean up be fore the application of the patina. Or if the steel wool in The EU is coated with some form of oil to keep it from rusting. But any traces of oils from hands or materials will interrupt the bonding of the patina layer. You may have to use an organic solvent to remove the oils and other material left behind during the clean up or chasing after assemble. Xylene (xylol) is one of the fastest working but is also a hot or strong solvent with all the Safety needs that should be done when using them. Isopropyl Alcohol is a slower acting one. Denatured Alcohol is stronger than Isopropyl Alcohol. Here in the US, Acetone is a favorite for final clean up after the rinse. Since it will suck up water in crevices and pits and indents in the surface.
If you do the etch it would be better after cleaning up again as not to contaminate the surface, and not embedding the grit and particles in the surface. It sounds interesting hope you can post some photos of your experiments.
Ok, thanks, again, it sounds very interesting, because the best plate i got it was sanded with a normal sand paper without touching it and after i had removed the plastic coat and washed it and let it dry to the air. So now reading what you wrote i see one big fault, cause last two plates i sanded them with steel wool and it looked clean, but it had been used before, so surely it had a lot of organic rests (BIG ERROR) but at least detected with your help. I will also use the acetone here, and will report here the results.
Many thanks
Use a weaker mix of the patina. Apply then rinse, apply then rinse. Let set over night. Ferric Nitrate should not peel off any time, Liver of sulphur should stick well too, would blotchy if metal is not evenly cleaned.
Ok, Warren it sounds good to take it easy working slower the patina and not wanting to do all the work just in one moment, but it was the way i worked with bronze and it really was different. I'll try to take it easy.
By the way, talking today with a plumber I asked him how did he think I could get more tooth on the surface before the patina. He suggested me, after sanding it, to apply a coat of an etcher, the ones they apply to the pipes before solder them ( it is a thick liquid), and to get it hot with the torch, after that, to pass a clothe and start working with the patina.
I will try it too, and report here how it went.
Thanks again
If by etcher it is the flux used to clean the copper before the application of the solder my answer would be NOOOOO! as you would then have to clean the grease based flux up. If you lightly sand the surface or use the plastic pot scrubbies or the 3m hand finishing pads.
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The brown(coarse) and red(medium) and the green in front are fine the top one with the scotch-brite on it is the pot scrubber pads, the other is the industrial version.
The flux or etcher as you call it will have to solvent removed even after heating. It is great for soldering pipe but it sucks for patina's.
Good to know it, i won't try the flux then. But I was thinking, how would it be to attack the copper to get the tooth with nitric acid, the one i have used to do the plates for etchings and engravings, it really attacks the copper,in fact it is called "the tooth" when you work with etchings ,and maybe it would depend on the time of exposure of the copper to it.
Again thanks for your attention
You just need a slight tooth nothing to deep or rough like you can get from 220 grit sand paper. You are correct that working and patinating bronzes is a whole different program and process.
You just don't have to over think this process. Once the patina is on, and dry along with the look you are after. You can seal it and then wax if you desire to.
It has been a while since my limited experience with printing from copper plates. The tooth from the acid might be to aggressive, if I remember correctly.