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Sunday, March 25, 2012

More Patina Experiments... This Time: Sealants

Decided to expand my patina testing to a major area of concern for me… sealants.

After which I spent some time just playing with applying patinas via my torch (I used my box of old crappy practice components… mostly bronze and copper metal clay pieces).

For the sealant test, I took six 24 gauge copper disks and cleaned them with Penny Brite then alcohol.

Then I textured them a little and dapped them into concave shapes.

Last step was to punch holes in them.

BTW, if I do all that manipulating after I clean the pieces (yeah, I don’t always think ahead), I wear latex gloves while I’m working so as not dirty the pieces again.

I then patinated the pieces with ammonia and liver of sulfur (for measurements see previous blog post ).

So I took photos of these pieces, along with the group of bronze and copper that were only heat patinated so that I can compare the before and after photos to see which sealants change the patinas the most.

The first sealant I picked up from my closet of “stuff” was Triangle Craft’s Sophisticated Finishes Primer and Clear Sealer. Couldn’t use it though as the directions state it is not for metal (but I still may experiment with it at a later date because I have coated copper pieces with this before).

Next up Minwax Water-Based Polyurethane. Another no-go. I’d like to steer clear of anything water-based since I think a water-based sealant would let in more oxygen than an oil-based one and it’s the oxygen that will continue to change the color underneath the sealant.

Then I grab my Mixwax Fast-Drying Polyurethane, but the writing on the can is too small for me to read so I hit up Google and try to research it. Hm… can’t find anything that specifically states it’s not water-based, but all the other ones ARE labeled as “water-based”, so I’m going under the assumption that this is not.

I made a quick and cheap contraption to hold the pieces as they dry. I took some heavy gauge brasswire and formed three pieces as shown below, then shoved the ends into a styrofoam square I keep on hand (these styprofoam things are awesome… I also use them to hold PMC pieces upright while they dry).

Then, after dipping each piece suspended from a thin piece of brass wire, I tie the thin wire onto one of the notches in my wire frame. Final touch is writing which number each set is, so I can match it up with my notes when I’m done.

Test #2 is Krylon Make it Last! Clear Sealer.

Had to go outside to do this one (it’s an aerosol). Swept a couple coats across the fronts and backs.

For Test #3 I’ve decided to go ahead and use Renaissance Wax. I want to compare, right?

The rest of my tests pretty much just turned into the Minwax versus Renaissance wax. I did the polyurethane on the right half of each piece (noticing some distinctive color changes immediately upon application) and Renaissance wax on the left halves.

So here are the results:

Here’s the phot showing the heat-patinated bronze and copper pieces before any coatings were added:

For the bits and pieces, the polyurethane is on the right and the Renaissance wax is on the left. The bronze piece on the far left is the back of the piece, but all the other ones are showing the front (and sorry they’re not in the same order in the photo).

I was so intrigued by the lovely shade of red this piece of copper achieved, that I decided to keep a strip of it down the middle for comparison. So on the right is the varnish, on the left is the wax sealer and in the middle is au naturel.

And here are photos of the fronts and backs of the patinated dome pieces before any sealants:

And after:

I’m thinking of watching these pieces and taking photos are monthly intervals to see if/how the colors continue to change.

But so far my conclusions are:

The varnish is neat except it leaves a very glossy shine. I may pick up a can of “semi-gloss” or “satin” for comparison.

The spray sealant seems to leave the piece feeling… artificial? Or coated? I can’t find the right words, but I think I’ll take the varnish or wax coatings over the spray sealant.

The wax leaves a nice feel to the piece, but I do think it dulls the color more than the other two coatings.

As can be seen in the bronze/copper scrap pieces, both the wax and the varnish significantly change the patina color. The lovely reds turned to lovely orange/yellows.

A lot of the very subtle blues and greens have disappeared.

I’ll keep experimenting and keep sharing the results with you.


  1. Clear coat is a big issue. I don't like to sell anything without a clear coat. But the claer coats are so unpredictable with different patinas. I am glad you are experimenting and posting for everyone to learn from!

  2. Thanks for sharing your sealant experience. I'm just starting out with the bronzclay and came across your blog. I like the look of the wax. It's a shame that you lose some of the colors when sealing. Also, loved your patina post.

  3. After fire polishing copper and getting gorgeous colors, I have never found anything that will preserve them. I have used Krylon water base matte spray which will protect the piece from wear. It does affect the original colors but does not yellow over time and drys well. My thought is to use the waxes that come in colors to achieve those original colors.

  4. Thanks so much for posting your experiments! I am going to try the LOS and ammonia on my next antiquing batch. Love following your blog :)

  5. Thanks so much for posting your experiments! I am going to try the LOS with ammonia on my next antiquing batch to be done. I really enjoy following your blog!

  6. Thanks everyone for the encouragement and the info.

    Please continue to contact me with the follow-up to any of your own experiments. We can all share the info!

  7. I used Vintaj sealer and lacquer from Rio Grande on a patinaed pendant and both irritated by skin in very hot weather. I had awful breakout on the place where the pendant rested on my neck.

    Anyone have experience like this?

  8. Nina, that's interesting. Do you recall which RG lacquer you used? I'd hate to think my customers would get a rash or be irritated by any of my jewelry. Yuck.