I varnish all of my jewellery with multiple coats of matt varnish and have spent a long time looking for the perfect varnish. I want my varnished pieces to still look like paper, but also to be as strong and as water-resistant as possible. I'm not expecting anyone to take a bath in a pair of my earrings but they do need to survive being worn next to damp skin, or being caught in a rain shower.
A gloss or satin covering is not appropriate for my current collection as it changes the look of the jewellery, giving it the finish of plastic. The perfect varnish should therefore be matt, clear and water-resistant.
I've done a lot of research on the internet to find out what other people use. For example here is an excellent article relating to papiermache objects. However, there are not that many (stubborn?) people out there trying to make properly water-resistant paper jewellery. Unfortunately some people make claims as to what different lacquers/sealers/varnishes can do without properly testing them. For example that a PVA type glue will waterproof paper - it will not!
So far I've tried more than 15 different kinds of varnish that have turned out to be unsuitable. Sprays are not good - they don't seem to cover all parts effectively, even after multiple coats. PVA type coverings, including those sold for decoupage, are unreliable, they usually stay tacky to the touch when dry and go sticky if they get wet. Other varnishes say they are clear but actually leave a yellow or chalky tone.
I test each varnish in the following way. I take a number of my card discs and varnish them with multiple coats with sufficient drying time in between. I've tried varying the number of coats and also tried a number of combinations of different varnishes on the same pieces. The varnished discs are then submerged in water. This is a harsher test than the reality of what my jewellery should survive in use, so should be sufficient.
Since I started making paper jewellery, I've kept researching new varnishes and combinations of varnishes to improve the quality of my pieces. My most recent experiments yesterday have extended the time a piece can survive submerged in water to over two hours. This result was achieved by layering two different kinds of varnish.