Ask Ginger: Sealing Metal Leaf

Does Swellegant sealer protect gold leaf from scratching and tarnish? What about paint on the surface of clay? And I’ve seen that you recommend DuraClear UltraMatte, will this work for sealing metal leaf? Grateful Clayer

Hi Grateful,

It’s a funny thing about using a varnish to protect something that’s on the surface of polymer clay. Polymer clay is plastic. And varnish is a very thin layer of another plastic, applied over it. That thin layer of plastic will easily be scratched off if you dig at it. Just imagine if you applied varnish onto a vinyl beach ball…you wouldn’t expect it to protect it from being punctured, would you? It’s kinda the same thing. Varnish will certainly protect metal leaf from being oxidized because it prevents air from getting to it. But it won’t allow the metal leaf to be strong as steel or anything.

For earrings? Any compatible brand of varnish should work just fine. But it won’t work for something that needs true durability such as a keychain or coaster or something that gets knocked around a lot.

As for paint, it is also a thin layer of plastic (with pigment) and nearly always scratches off easily. Varnish will only attach to the paint, which doesn’t make a durable surface. As with metal leaf, varnish over paint will help keep the paint clean and bright, and works great for earrings or low-wear items. But nothing will keep paint from scratching off bracelets, keychains, and zipper pulls. You can read more about painting polymer clay here.

One thing to note. Matte varnish will make metal leaf look frosted. It won’t be shiny. You can see an example of that phenomenon here.

In your photo, you have incorporated the metal leaf inside the clay, itself. In this case, it’s only exposed on the surface and where the metal is covered with clay, it won’t need sealing. I often don’t seal at all in cases like this.

One thing I can suggest is that you avoid using aluminum or copper metal leaf. These will tarish, even if they’re sealed and even if they’re mixed in with the polymer clay. Here’s a veneer that I made MANY years ago (2003 or thereabouts) and it’s been tarnished like this for a long time. If you’ll note, the part INSIDE the clay has tarnished, the part coated with Varathane on the surface is fine. 

metal leaf mokume gane

Metal leaf from the Mona Lisa brand is made of real metal, usually copper or aluminum. But there has been a recent proliferation of cheap no-name “metal” leaf from China in recent years. This does not appear, to me, to be metal. If is some sort of metal oxide layer and does not tend to tarnish in the same way as traditional metal leaf. I love using this type for polymer clay because it comes in a variety of bright colors, it crumbles easily for mixing into clay, and it doesn’t change color with baking or tarnishing.

Not sure which you have? Try this. Drop some vinegar and salt on a piece of the leaf. What happens? If it changes color or tarnishes as it dries, you have real metal. If not, it’s the other stuff. Honestly, I’d avoid using real metal. Here is a package of inexpensive “metal” leaf from China, that I purchased on Amazon.

inexpensive metal leaf from China

A Second Question

Hi Ginger, I read your answer about sealing polymer clay when metal leaf was used. So, as I understand you don’t need to seal if you use the leaf for marbling which is so great to know as I was struggling with this issue. My doubt is, which method of sealing would you recommend if the entire surface has gold leaf on it (not made of real metal, but the Chinese/Amazon ones). I am asking cause the sealer would have to stick to the metal leaf itself not directly to the clay. Thanks in advance for your help. Sue from Spain

Hi Sue,

This is a great question. There is a tendency to want sealers and varnishes to protect our polymer clay from all damage and wear. And this is just unrealistic.

Polymer clay is vinyl, so it’s pretty resilient. But metal leaf is not. It’s a very, very thin layer of a very, very brittle material. You can apply it and it sticks just fine to raw polymer clay, and it stays there just fine after baking. But it can be scratched off with very little difficulty. 

Applying a varnish over the top of the gold leaf just applies another thin layer. And as you accurately point out, it’s only attached to the leaf…so how strong can it be? You’re right to be skeptical. It’s not a strong situation and this won’t be very strong!

But for low-wear items like earrings that are treated gently, varnish should provide a strong enough surface. People won’t be (or shouldn’t be) digging at their earrings or tossing them in the bottom of their purse with their keys. (And if they do…is that our issue?)

For an even better surface, coat with resin. That makes a very durable surface.

Also, if you’re coating the entire surface, rather than using leaf, try using mica powder.

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