Effects of constant running water on enamel

25 september 2014 // Door webmaster //
Jenny Gore
I have been asked about the effects that constant running water would have on enamel in an outdoor situation as in a water feature (of course as soon as possible!).
I said that I believed there would be no problem and that the edges of the copper would become greenish etc.
They need some assurance from someone who has done something similar some years previously that all will be well. Do you know of any such piece? I wondered if I should use lead free enamel? I would have to buy this in as I still use my extensive stocks of Thompsons leaded for most of my work. I do have quantities of Schauer leaded transparents; do you think Schauer would be any more resistant to any slight etching effect from any chemicals that may be in the water?
Philip Quanjer
Here is my penny worth of thoughts about this. Enamel is glass. Considering that glazed earthenware has been recovered in pristine condition from the bottom of oceans after centuries of exposure to sea water, I do not think that even salt water would harm enamel. Those ancient glazes may or may not have been lead bearing, I have no idea. I do not know what the water feature will be like, but suspect that if the water does not run constantly over the entire surface, in the long run calcium deposits might develop. If there were cracks in the enamel surface, or when they developed in the long run, I would expect that these wold become conspicuous. And as you said, the metal would in the long run show the wear and tear of exposure to the atmosphere and water.
I recently discovered that the Schauer line is being continued by Milton Bridge in the UK. I will ask them about the acid resistance of the various Schauer enamels. As to Thompson: I will ask them too.
Allan Heywood
The way I see it the possible effects can be classified into two main categories, viz:

Physical effects

  1. abrasion – gradual wearing away of the enamel by particles of dust etc ( which are pulverised minerals ) of varying degrees of hardness which might be suspended in the water.
  2. expansion/contraction due to variations in temperature between night and day, summer and winter etc leading to microcracking and possible eventual delamination of larger areas. Any cracks would of course provide access to the base metal and the less vitrified inner mass of the enamel which is “softer”, porous, and thus more prone to abrasion and chemical attack.

Chemical effects

  1. etching of the surface by acidic or basic waters
  2. gradual buildup of carbonates and/or sulphate salts from mineralised water.

Of course any ( or no ) combination of the above might ( or might not ) occur – once you add in the other variables of type and make of enamel, type of base metal, type of fasteners, contact directly or indirectly with other metals that might allow electroetching of the base metal to occur you have a completely unpredictable scenario. Think of the effect of years of water dripping from a leaky tap into an enamel bathtub. The Thompson leadfree range is supposed to be more acid-resistant than leaded enamels, and the Ninomiya enamels I’ve used are very acid-sensitive (for what that’s worth). None of which would stop me from going ahead with the project, because the only way to know whether it’ll work in a particular set of circumstances is to actually DO it.

Barbara Pelowski
I have had some enamel panels — Thompsons leaded enamel on copper, on my garage door outdoors. Over the years they have been exposed to rain, snow, very cold [below zero] temperatures and summer heat for 10 years or so. They seem to be doing fine. I am not sure about the effect of constant water. I attached them with 100 % silicone caulk commonly available at hardware stores.
My name is Monica and I did some work of this kind back when I still living in Mexico, I used Blithe enamels and they lost their brightnessl this is like when you find a piece of glass by the ocean, they become dull. This was 15 years ago.
Bill Helwig, chief Technical Consultant at Thompson
We find that the webmaster’s reply is a very good answer. Lead-free is as good as, if not better, than lead bearing when it comes to acid resistance. Suggest tests be run on the enamels to be used.
Victoria van den Bergh
Am I right that this enamel piece will be put into a fountain? That reminds me of our old bathtub: quite immune to decades of exposure to: running water. Only if the stopcock drips rusty water a brown-yellowish stain develops which can be easily removed with an abrasive. When placed outside I would sooner expect discolouration due to algae than enything else.
I have nothing to contribute re lead bearing or lead free animals, but the fish in a pond might have there own ideas about this.
Woodrow Carpenter
Most bridges over navigable water ways have so called, ‘river gauges’ on their piers. This is so boat crews can see how deep the water is. They are long rulers with marks in feet or meters. Many are porcelain enameled steel. The enamel should, at least, withstand 10% citric acid for 10 minutes without loss of gloss. It is not a matter of containing or not containing lead. Lead free can be made more resistant to acid than lead bearing.
Woodrow Carpenter
Mr. Merrill
This from a conservator of objects at a musuem. Good question. Leaded or lead-free enamels should have little to do with any corrosion which may occurr. The most likely effect is that the copper will corrode — far more obvious than the glass being etched. Corrosion may well occurr with exposure of the copper base to oxygen, moisture and chlorides or other salts dissolved in the water — and only the exposed copper is likely to get corrosion which could undercut the enamel over time. Furthermore minerals in the water could be deposited on the enamel surface which would obscure the design. Both of these concerns depend primarily on the water quality — not the kind of enamel you are using. If this enameled object is exposed to cycles of wet and dry periods this would accellerate the build up … very high or low ph might etch the glass.
Kees Pynappel
We have enamels outside in wind, rain and snow for 6 years with no problem, we have used both mentioned companies enamels. But I think an Email to both would give the answers. Give it a go, good luck.
Kind regards.
Thérèse Luycx
As regards enamel exposed to water and the environment, my experience is that they mix very well, but the material that you apply the enamel on matters. Jan de Valk has finished many outdoor projects, one of his objects (on stainless steel) is even in the water of a moat in Amersfoort. The photoshop of my father, now of my brothers and nephew, has an enamel doorhandle which has been indestructible for 40 years.


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