Hi guys. I am having a really hard time finding some sort of sealant or coating to apply to the copper sheets I am coloring with a torch. The lively and vivid reds and oranges and blues just instantly dissapear once it's applied. I've seen the steel pieces with a clear coat and it just makes the colors shine.
What out there will provide some UV coverage and still keep the color I worked to get?
Any help would be greatly appreciated.
Thanks.
SF
what kind of a sealant are you using?
Minwax Fast-drying polyurethane (Clear Satin) from HD or other left a slightly dead hue to polished copper and totally destroyed any real color qualities.
Nikolas outdoor clear #8321 Lazquer from Capitol Metals was slightly better for color but still not good at all... though it really protected polished copper a lot better... then another Nikolas (the UV boat brass lacquer) put a pretty durable finish on copper... again the same color desaturation occured.
Then I was lead to Ultra Base 7 (cc648 from Sherwin Williams Automotive finishes) KUT-IN Acrylic Clear by spectrum over in Mesa. The color again simply dissipeared, but I suspect it's coating will outlast the other two.
All four were obviously spray can application. I know to place wax over my patina pieces, but I'm looking for something for my bare metal pieces that would be a more durable coating (rather than a finish) than wax.
Thanks.
sf
First off, welcome to the forum Scott!
Its sounds like you have two problems. One, you are looking for a durable UV clear, and two, you would like one that won
You are dead on regarding the spectrum of color loss after initial spray. I primarily use an O/A setup and vary the compositions of the mixture as well as proximity and duration to achieve the colors I want. O/A for me has been much better than Propane, Mapp, or NG. I've actually found much greater color control with hotter flames than cooler ones and being patient with the process. Of course different types of pre-treatments make a difference as well... various acid/alkaline rubs or solutions from chocolate to bannana peels to whatever crazy concoctions one can think of.
I was hoping that the culprit was an acelerator or propellant in the can and that there would be a manual application process of solution which would eliminate the surface reoxidation reaction and still bond to the metal. I've seen coatings on steel that protect the surface while maintaining extremly vivid colors in the Red, Green, and Blue regions.
Are you suggesting a cooler flame would change the structure of the initial patina, assuming I can achieve the same color with it? I thought a hotter flame would provide for less gas oxidation as the surounding induction bloom was larger?
I haven't tried straight induction heating yet as that would require building a tool... unless you would have any insights into the temperature that a Milwaukee or other heat gun operates at?
Thanks for the help. It really sounds like you know what you're talking about.
sf
Actually, I just read something about melting a polyester powder over copper. Anyone had experience with low temp melting plastic coatings?
sf
Scott, I'm suggesting you try a cleaner flame not cooler. Propane coming out of a weed burner is very hot and will anneal quickly if you are not careful. I have just found that the slower and cleaner you go, the better the results. Just don't expect miracles.
I have never tried to melt plastic over metal and probably never will. I have seen it done and it looks to "plasticy" to me. What temp does it melt at? It might change your color as well.
I don't know much about the plastic process at all and haven't researched the melting point, though it sounds like it might be less likely to change the color as the reaction isn't chemically reactive as the components in the Incralac or Lacquer, which is where I believe the color desaturation occurs. It seems to me the temp would be pretty far below even the coolest flame. I just saw a link somewhere talking about it. It's something worth giving a shot at if no-one says "DON'T, I tried and it sucks". The worst that can happen is junking a test piece. And if it works... then FANTASTIC MATE !! There is always a ray of hope. (I Hope;-)
Plus, as a concept, even if the polyester doesn't leave a crisp enough look, there might be something out there that would have a low enough melting point with an extremely low viscosity at temperture with just enough 'stiction' to copper which doesn't carry the reactivity of a enes, anes, ols, and ates that I suspect are the cause of the desaturation.
It's a lot of work, but it may be able to act as a sort of intermediary layer which protects the color from the final coating which will leave the surface finish at a desired, hard and invisible state if the underlying base is clear enough.
The color I'm very happy with. What I want to focus on is protecting it once I've got it where I want it.
sf
If you decide to try it, take some before and after photos and post them here. I would love to see your results.
Good luck!
Some spectrum loss is a sad fact of life with any coating because the light is diffused to a degree. I have experienced the same problem you describe with coloring steel (using Minwax spray polyurethane as the over-coat) and did not like the results. Try spraying a bit of WD40 on the copper after you color it and see if you like that look. An oil film can be extremely thin so will give some initial protection without too much refraction change. If it is satisfactory, wipe the excess with a clean cloth and spray lightly with a synthetic finish. HD sells a product called Polylac that also looks promising. I have not tried it personally so can only pass on hearsay from a friend that it worked well for him in a similar app. Good luck and let us know what you discover.