Will Humidity Hurt Polymer Clay (Things to Consider)

Polymer clay is an appealing medium for outdoor crafts. Not only is it malleable and incredibly versatile, but it’s also quite durable, as well. It can withstand rain and various types of weather conditions. 

Polymer clay makes an excellent option for handmade garden decorations and other outdoor projects. It’s completely waterproof as-is and it does not require sealing for these purposes unless you are embedding mixed media. Over time, sun exposure may change the appearance of some colors. 

Is polymer clay waterproof?

Polymer clay is completely waterproof, cured or not. That is because it is oil-based, not water-based like most of the air-dry clays out there. With the exception of some clay brands and darker colors that are slightly more porous, polymer clay does not absorb, hold water in or mix with it.

These characteristics make it really easy to clean and the perfect material for outdoor art projects and snow globes. Since it isn’t tested for aquatic use, it isn’t advisable to use polymer clay for submerged aquarium creations.   

Is polymer clay suitable for outdoors?

Polymer clay can be used for crafts that are intended for outdoors, like garden art, mosaics, bird houses, and sun catchers. The rain will not ruin it. 

However, extreme heat or cold temperatures may affect it over time, so it’s best to bring the pieces inside temporarily (there are many people that don’t, though). For example, some colors of polymer clay may darken over time with constant sun exposure and others may fade significantly (like Sculpey Granitex). 

Paints and sealers may not hold up well over time when exposed to the elements — they may peel, crack, or discolor. Some finishes may also soften when they are exposed to heat. 

Can polymer clay be submerged in water?

Polymer clay can be left continuously underwater without any problems. It will not deteriorate. Not all paints and sealers will fare the same with prolonged water exposure. That being said, although it makes a great snowglobe addition, polymer clay isn’t the best solution for making things like aquarium decorations because it hasn’t been definitely determined as safe for fish. 

Do you have to seal polymer clay?

In most cases sealing polymer clay is unnecessary.  Once it is properly cured polymer clay is very durable — it doesn’t require any special surface treatments to make it waterproof. In fact, painting it or adding a sealer may actually cause the project to be less durable in the long run because the surface treatments are more likely to have issues with humidity.

Sealers (also called varnishes) are used for protecting only the surface or the top layer of your piece when you have applied a material that can easily be rubbed or scraped off in time like acrylic paint, glitter or embossing powder. So technically you are not even protecting the clay, but the less durable technique you have applied on top of it. 

Sealers are also used for the creation of gloss or matte effect. They are the perfect solution if you are not satisfied with the gloss level of your piece after you have baked and sanded it. 

If you want to intensify the colors of your project, varnishes are the way to go as well. A thin layer can saturate the colors so they pop out more. The same is valid if you are working with translucent clay – it will make it even more see-through and deep.

Use a sealer only when you are completely satisfied with the look of your piece as it is. Even though a finish will make it better, it will also accentuate any imperfections. So do not use it on a piece that has many fingerprints and dents, for they will be even more visible after it dries.

If the surface of your polymer clay is not smooth, whether that is a desired effect or not, keep away from varnishes. If your project has a lot of texture, little bits of the coating will collect in the cracks and the end result will look sloppy even if that was not the case before the sealer.  

What sealer do you use on outdoor polymer clay creations?

Some artists like to use the outdoor formulation of Varathane for projects that are intended for garden use. It’s important to make sure that you are using the water-based version (there’s also an oil-based one). 

What happens if you get water on unbaked polymer clay?

It is completely safe for water to get on your unbaked polymer clay piece. It does not absorb in it, but stays on its surface. You can even use water as a technique to transfer images on your piece.

To do that, you need an image printed on paper with a laser printer. Put the paper on top of your piece in the area where you want the image to be. Make sure the printed side is facing down.  If you want to transfer a text, print it mirrored so it will be readable when transferred on the clay.

Press the paper lightly so it sticks just a little bit on the clay surface. Dip a paper tissue or a paintbrush in water and dab the paper thorough until it gets damp. Squeeze out any air bubbles by slowly pressing the paper with your finger towards the edges of the sheet. 

Be gentle. Putting too much pressure can cause the paper to tear apart, destroying the integrity of the image.

In this stage you should be able to see briefly some of the lines of the image. Continue putting water on until the paper is moist enough but not dripping wet. The thinner the paper is, the less water it will take to complete the transfer.

Wait for the paper to dry (usually takes 5 to 10 minutes) and gently start rubbing on it with your finger. Rub on small patches to avoid damaging the image. Little fibers of paper will start to come off but the print should remain on the clay. 

When you are done removing the paper, you can cure your piece straight away. There’s no need to coat it. It will keep its integrity even in the oven.

Can you bake polymer clay that has water on it?

If you have watered your unbaked clay, make sure it is completely dry before starting to cure it. Water will heat up in the oven and form steam. This can trap air bubbles just below the surface of your piece. 

By letting your polymer clay dry, you save yourself the time and effort of removing the bubbles when your piece is cured. 


Polymer Clay Garden Art

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