UV Impact on Colored Patinas On Bronze

Arguably, from a door handle perspective, Florida can be one of the most demanding climates. The state is a peninsula surrounded by sea water and its latitude yields many days of sunshine and not surprisingly is home to many of our clients.

UV Impact on Bronze

When we hot patina a door or cabinet pull we heat the bronze with a torch and apply successive coats of pigment suspended in water to the metal surface which absorbs the pigment left after the water  evaporates. The patina absorbs UV and this leads to a chemical change that breakdowns the bonds between the pigment molecules making the color appear less vibrant. The lizard levers below will fade over time with UV exposure so what are the options?

Photo of lizards at patina stage before sealant applied. Photo courtesy of the photographer Maria Ramirez-Adams.

 How to lessen UV impact

Clear polyurethane resin and polyester offer 2 different ways of sealing and protecting the color.

Polyurethane acts as a UV blocker and as a resistant physical barrier that shields the color beneath. It blocks the UV by absorbing, deflecting and scattering the UV away from the metal surface thereby slowing chemical changes in the patina.

Clear polyurethane resin also creates a physical barrier that shields the layers beneath from UV and also from salt and environmental contaminants that can degrade the patina. The resin is typically sprayed onto the surface and air dried rather than baked.

 Polyester versus powder coat

Polyester is also an excellent sealant for protecting metal from UV and salt and environmental degradants. The practical difference lies in how they are applied and cured.  Polyester is applied as a powder using an electrostatic process. The piece to be coated is attached to a copper frame or rod which negativley charges it. The applicator, which is like a spray gun is positively charged and when fired the gun sprays powder onto the surface of the object. In simple terms think of physics 101 when a magnet is used to attract iron filings. The powder bonds to the surface of the object. To make the bond more permanent the coated object is baked  to a temperature of 350 to 400 degrees for at 10+ minutes. With polyurethane the finish cures over a longer period often taking 5 to 7 days to complete. The Geckos shown here were both hot patinaed with a green pigmented solution but the top gecko was first dipped in a cold dark solution and then both were coated with polyester and baked. Polyester makes the pieces a little plastic in appearance but it does offer a resilient seal that will last for years.

Door Handles For Yachts - 316 Stainless Steel Passivation versus Rust

In a previous post we analyzed the components of grades 304 and 316 stainless steel that make them rust resistant. Both contain chromium, and nickel and together these elements enable the outer surface of a casting to form a thin protective layer of chromium oxide that protects the lower surfaces and acts as a barrier to rust. However, only 316 stainless steel contains molybdenum which is a metal that specifically helps prevent rust caused by exposure to sea water or sodium chloride which is why this is the preferred steel for yachts and beach homes and why it is aptly described as marine grade stainless steel.
While 316 stainless steel in its production contains the necessary properties to prevent corrosion the thin nano thick protective film can be degraded and while the presence of nickel does help this layer self-heal and re-form the protective chromium oxide there may be occasions when the fixture will need to be treated.
Several years ago, we heard from a homeowner in Florida who reported that her 316 stainless steel handles was developing rust. On inspection we could see that sand and grease had adhered to the handle and it was these contaminants that were rusting. The handle itself was still sound and showed no structural decay, in other words, the steel was not actually rusting.

Morphic Entry Lever In 316 Stainless Steel Compare With Similar Handle After 10 Years In Image Below

This type of surface contamination can also occur when the stainless steel is machined especially if there are iron based metals in close proximity.
In both cases the surface can be cleaned or “passivated” by being immersed in a citric acid solution which will remove most contaminants and allow the surface to self-heal by forming a new passive layer of chromium oxide. I strongly recommend that you do not do this yourself but find a reputable passivation company in your area.

Morphic Entry Lever With Blue Powder Coat 10 Years After Installation

Marine grade steel is not only durable, but it polishes well and can be enhanced by using different finishing techniques or by adding color through powder coating. Powder coating is a durable way to add color to any stainless-steel fixture especially if it intended for outdoor use.

Marine Grade Door Handles for Beach Properties - Part 1

If you live at the beach or own a yacht you are probably aware of the corrosive effects of salt air and sea water that can eat away at iron causing it to rust and degrade. What causes this to happen and what metals should door handles be made from to avoid this fate?

Our door handles and cabinet pulls are cast either in silicon bronze or 316 stainless steel and both are good choices for ocean or beach environments as they both oxidize in a good way.

To understand corrosion we first need to analyze the alloys that make up stainless steel and bronze.

Stainless Steel

Describes a family of metal alloys the base or main alloy being iron. The other important components are carbon, chromium, nickel and molybdenum and the last 3 make 316 stainless steel corrosion resistant.

Water causes iron to rust by combining with carbon dioxide in the air to produce corrosive carbonic acid which as it dissolves the iron creates a layer of iron oxide or rust.
Stainless steel contains the metal chromium which when exposed to oxygen in the air becomes unstable and combines with the oxygen to produce a thin protective film of chromium oxide. The film is passive and does not harm the metal but forms a tight film that clings to the surface effectively sealing it. The thin layer of chromium oxide adheres to the surface forming an almost impenetrable film that prevents harmful iron oxidation from occurring.

The Nickel component plays a supporting role and it enables the chromium oxide to rebuild and self-heal if it is damaged, it helps the chromium rebind with oxygen to create more protective chromium oxide.

While 304 and 316 grades of stainless steel contain chromium and nickel only 316 contains molybdenum a metal that is particularly effective at preventing corrosion caused by sodium chloride that is present in sea water. The salt content of water speeds up the corrosive effect of carbonic acid and molybdenum seems to slow this process down thereby helping prevent corrosion.

We make our Ergo and Morphic door handles in 316 stainless steel, the alloy is more expensive and harder to machine and finish than other grades but it’s superior corrosion resistance justifies the price tag.

Luxury Home Bathroom Accessories

Whether it be the guests’ powder room or the master bedroom spa choosing a unique soap dish or intricately detailed towel rail can finesse to even the smallest space and can make a striking addition to even the most modest bathroom makeover.

While this custom towel rail was designed to be used in an opulent yacht setting, by choosing a nature inspired design and a more rustic bronze medium this unique towel rail is both modest and luxurious. Had this piece been rendered in polished bronze the appearance would have been garish.

Polished towel rails and other bathroom accessories do have their place in any bathroom makeover but consider using a more sophisticated two-tone finish such as the one used below on the Ergo towel rail where the polished facets are softened by satin finished contours. The effect is labor intensive requiring  each piece to be firstly hand polished and then masked so that the contours can be subdued by hand brushing, the result though is a subtle and very tactile towel rail.

Fluid lines define the Ergo Collection

Our contemporary bathroom accessories in both the Ergo and Morphic collections are typically ordered in stainless steel a medium that plays well in any contemporary bathroom makeover. By comparison the more classical Hedgerow and Willow towel rails and soap dishes are used in both transitional and rustic bathrooms. That said the Ergo style can work equally well when cast in bronze and finished with an oil rubbed antique patina which gives it a more arts and crafts appearance.

Hedgerow Tree Towel Rail

Unique Bronze Towel Rails

We are known for casting unusual custom door handles and our creative designer clients often will come to us with their ideas for a new concept which is how the dialogue began with a design group in Florida who specialize in luxury yacht interiors.  As I am not well versed in specifics of yacht interiors I had assumed all yacht fixtures needed to be very light weight and made in corrosive resistant stainless steel, so was pleasantly surprised when we were asked to use our fiddlehead fern motif to create towel rails and robe hooks  in solid bronze.

While the major component of a towel rail is a simple bar the fun and artistry comes in creating wall mounts to support the rail. However, with this custom project  we were also tasked with making a curved towel rail to fit the wall surface in the master bathroom which was no easy feat given the very specific radius of the wall. In this post I wanted to show we re-invented the fiddleheads to change their function from gently protruding cabinet pulls to wall mounted supports able to take the weight of a solid bronze towel bar.

Cast in solid bronze and finished with a dark patina to accentuate the shape. The images here are the end result of a collaborative process with our very creative designer client. Below is the drawing that helped us understand the radius needed to fit the curvature of the master bathroom wall.