You know the sheets of metal leaf, gold leaf, metallic foil, and metallic film we sometimes use with our polymer clay art? First off, what is it? What’s the difference between types? And why does it sometimes turn dark or brown? Read on, my friend, and I’ll tell you what I know.
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Metal Leaf
Metal LEAF is a super-thin, wispy, fragile sheet of metal. It traditionally comes in gold, silver, or copper colors, but can now be found in blue, pink, green, etc. A common brand name is “Mona Lisa” by Speedball, but there are many inexpensive brands coming from China. (See more about this leaf below.)
Metal leaf is very useful in polymer clay, applied to the surface to add metallic highlights. When metal leaf is applied to the surface of polymer clay and then rolled thinner, you can create cracks or crackle effects. You can also mix metal leaf into polymer clay to create metallic veins or speckles, as I showed you in the Watercolor Agate tutorial.
Metal Foil
Metal FOIL is a plastic carrier sheet with some metallic coating applied. It’s also called transfer foil. The metal coating is often applied to lettering or designs, either by adhesion or heat, and then the plastic sheet is peeled away. This is often how printed paper or fabric gets metallic lettering. Common brands are Pebeo Gedeo or iCraft Deco Foil.
This material comes in every metallic color, as well as cool patterns, iridescent effects, and glitter finishes. Some brands can transfer to polymer clay, and when you can get it to work, it’s great. Sadly, not all brands adhere well to polymer clay. Nail foils are similar, but sold to nail artists, and often have flowery designs on them. They’re not always metallic.
Metal Film
Metallic FILM is generally just a metallic coating on a plastic film. Mylar is one brand name for this material. It’s what they make foil balloons out of. The metallic coating is part of the plastic and is not transferred to another surface. This material might have use in some of your creations, but is typically not used very much. It is typically applied to the clay and integrated in, like a window. The plastic may change during baking, giving unpredictable (and even interesting) effects.
Confusing Terminology?
These are three very different things, used in very different ways. The terminology is usually distinct in English. But things get wild in other languages, and the term FOIL or FOLIE gets used for all three things (depending on the language). This is because the words foil and leaf have a lot of linguistic overlap that you can see in words like foliage, folio, and phyllo. Some regions also refer to any of these as “metal paper”, which further complicates things because no paper is actually involved.
Additionally, Amazon listings are notorious for using many similar keywords to increase their search rankings, but this means the titles can be quite confusing about what you’re actually getting. It seems that the term “foil” is used nearly universally in these listings, but artists and craftsmen have referred to this material as “leaf” for centuries. (And yet we use the term foil for aluminum foil, so go figure! Language is bonkers sometimes.) I expect that confusion in the terminology will continue to blur the understanding of the distinction between these two materials.
About Metal Leaf turning Dark
Historically, gold was the first type of metal leaf because gold is highly ductile and can be beaten thinner than other metals. Gold leaf was applied to decorative elements (even entire domes) in a process called gilding. Real gold does not tarnish, and we’d love to use it for our craft work, but it’s awfully expensive.
Nowadays, we use composite metal leaf that’s made from cheaper metals. Silver colored leaf is generally made with zinc, while gold and copper colors are made with copper.
A drawback of composite metal leaf is that it can tarnish or discolor. To prevent this, it’s commonly recommended to seal it with varnish. However, this often does not work, and you find that the metal leaf has turned dark despite being sealed. This can happen when it’s used on top of the clay or when it’s mixed into it.
A common cause of this is the varnish itself. If your varnish contains ammonia, it will darken your composite metal leaf. I’ve found that some metal leaf will darken in time, no matter what you do. Two of the three beads below have metal leaf mixed in, and they darkened within six months. The coating on these beads was liquid clay, so no varnish was used.
There’s Another Type of Metal Leaf
There’s another type of leaf on the market in recent years that is called metal leaf, but I’m not 100% sure what it is. The kind I’m talking about is readily available on Amazon or other marketplaces specializing in “cheap stuff from China.” It is about 3″ (8 cm) square, each leaf comes in a thin paper sleeve, and it’s generally sold in packs with several bright colors. Here is an example and here’s another with even more colors.
This type of metal leaf is quite crumbly (much more so than regular metal leaf), flies everywhere, and can even be crumbled to make fine flakes resembling glitter. It does not seem to tarnish or darken at all. The bright colors CAN fade in the oven, though, so be aware your pinks might not stay bright. I’ve also found that the pink color can bleed into polymer clay when baked (possibly because a lake pigment is involved), so be aware of that.
Testing Your Metal Leaf
How can you tell which type of metal leaf you have? Well, if you have actual elemental gold leaf, you know it, because you paid dearly for it. Gold is pricey stuff at the moment! But to distinguish between composite metal leaf and this newer crumbly type of leaf, try this test.
Place a piece of each metal leaf on a piece of glass or a ceramic tile. Now mix up a little concoction of lemon juice and salt. Pour some of that on each sample (don’t let the samples touch). Cover each with some plastic wrap and let it sit overnight. Composite metal leaf will tarnish or even disintegrate. The other type will not darken and tarnish.
I’ve found that this newer mystery leaf is excellent when used in or on polymer clay. Isn’t that fun? Now go see what types of metal leaf or foil or sheets you have.
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