Shells can be great for all kinds of decor. You can use them in craft projects or just add them to a decorative bowl, vignette or tiered tray.

You can buy beautiful shells from craft and decor shops and these are usually highly polished and already glossy and vibrant. Some shells are not naturally quite so “display ready” and some might benefit from a little zhuzhing up first. You might already have a stash of shells somewhere that you collected from a beach years ago. If you are thinking of collecting shells now though please do bear in mind that in some parts of the world it is illegal to remove shells from the beach.

I had this little collection of clam shells saved from a meal in a restaurant. These rather plain and ordinary looking shells are quite sentimental to me. On our holiday last year, while in Canada we had a lovely big family meal. I sat next to my elderly aunt and we both had the pasta seafood dish. At the end of the meal we both automatically started wrapping our empty shells up in a paper napkin to take home, laughing together about how neither of us could leave anything like this behind because you never know when they might come in for a craft project! Sadly Auntie Cecile passed away at the beginning of this year (I created this heart embroidery design in her memory) so these dull clam shells are the embodiment of a lovely memory and I wanted to do something with them.

Why might you want to seal your shells?

Your shells might not have bright or vibrant colours, especially if they are saved from a meal like my clam shells. Sealing them can bring out the colours and make them more beautiful. It can also help to protect them and make them more durable.

Cleaning your shells

You’ll want to clean your shells thoroughly before you use them for anything else. Pop them in a bowl of warm water with a little washing up liquid (dish soap) or a little bicarbonate of soda (baking soda) and give them a bit of a scrub. A old toothbrush is good for this.

I’ve seen lots of people recommend a bleach and water solution for cleaning shells but I found the warm soapy water did a good job and the bicarb of soda version is helpful if your shells have a funny smell. As bleach is harmful to the environment it seems best to avoid using it whenever possible.

Sealing the shells

I tried 10 different methods to seal my clam shells, some definitely worked better to bring out the colours and make them more shiny than others. I literally pulled out everything I already had in my craft stash that I thought might work and gave each product a try. I also tried sealing a shell with baby oil but for some unknown reason the baby oil isn’t in this photo, not sure what happened there?

Let me go through each of them now and show you the results.

All the products were applied to a clean dry shell with a small paintbrush (with the exception of the baby oil, which I applied with a scrap of fabric and the sealant spray which obviously I sprayed) and then left to dry. I’ve photographed each alongside a plain original unfinished shell so you can see the difference. The sealed shell is on the left and the unfinished shell is on the right in all these photos.

Mod Podge

I tried 2 types of Mod Podge, Matte and Sparkle.

Both types of Mod Podge went on easily and smoothly. As you might expect the Matte Mod Podge gives a virtually undetectable matte finish. The Sparkle Mod Podge gives a really sparkly glitter finish. This type of Mod Podge is one of my favourite ways to apply glitter because it is so mess free, you really don’t get any of that glitter shedding that so often happens. Neither made much of a difference to the colours in the shell.

Decoupage Glue

The Decopatch decoupage glue I had seems very much like Mod Podge to be honest: the smell, look and feel seems the same, but the one I had is described as glossy so I thought it was worth a try. The sealed shell had what I can describe as a light sheen once it dried. The colours do seem brighter and more distinct.

Rustoleum Crystal Clear

This Rustoleum Crystal Clear Gloss spray is favourite craft sealant of mine, it is easy to apply and I’ve always found it gives a lovely hard wearing glossy finish to all sorts of surfaces.

After just one coat it gave the shell a lovely shiny finish and an increase in the depth of colour.

Vernidas Varnish

This Vernidas varnish is intended for air dry clay, I happened to have it so thought it was worth a go. It says glossy effect on the bottle and they are not lying! This was the glossiest, shiniest finish of all the methods to seal shells that I tried. It took a little longer to dry than the other methods but if you want shine this is a great product.

Clear Nail Varnish

Clear nail varnish gave this clam shell a beautiful shiny finish and a lovely depth of colour. This is a great option if you don’t want to be going out and buying more craft supplies. I used a simple base and top coat from OPI but I imagine the results would be the same with any nail varnish.

Spectrum Noir Glossy Highlights

Glossy Highlights from Spectrum Noir is a papercraft product, described as a clear gloss medium intended to add dimension. You can add a blob onto small embellishments to add a 3D element, use it as a glue for adding beads, sequins etc or it can be used as a protective coating.

To be honest I was a little surprised that this shell didn’t come out more shiny and glossy. When I’ve used Glossy Highlights before on paper the results have seemed more noticeable than they are here. Compared with some of the other products this shell ended up with more of a sheen than a shine.

Baby Oil

Baby Oil or another type of mineral oil is widely recommended online to give shine and durability to your shells. I applied a little with a scrap of cotton fabric but to be honest this one was a little disappointing. There was a slight sheen at first but as the oil dried the shell looked exactly as it had before. I thought it would make more of a difference to the shells colours and shine but it had very little effect. There is so side by side photo here unfortunately as I tested out this mineral oil on my last shell!

Cold Wax Medium

This is a slightly random product to try to seal a shell. I had some of this cold wax medium left over from sealing the art project I made with my late grandma’s paintings so I thought why not give it a go and see what happens. Nothing! That’s what happened! To be fair the main selling point of the cold wax medium when used to coat a painting is that it doesn’t change anything on the surface it covers, paint colours remain the same and nothing smudges so this is to be expected. The Cold Wax Medium gives a completely matte finish, unless that is what you would I really wouldn’t bother with this one. Save this product for the job it is intended for - sealing and protecting paintings - as it does that really well.

Copper Enamel Paint

Another coating idea that might seem a little unexpected, it certainly didn’t give the the results I was expecting anyway! When I’ve used this Plasti-Kote copper enamel paint before I’ve found it quite thin and it’s needed several coats to give any significant coverage. With that in mind I thought it might give the clam shell a coppery sheen but still allow some of the shells original colour to show through. No. That is not what happened! I’ve ended up with a copper painted shell. It’s actually really quite lovely and this is an experiment after all so it’s all good but not the light sheen I was anticipating.

Conclusions from my sealing shells experiments

If you have plain dull shells you can definitely give them a bit more zhuzh by sealing them. A shiny finish will bring out any colours and make the shell more vibrant.

If you want shiny shine shine then a glassy varnish like Vernidas is hard to beat, with the crystal clear spray and clear nail varnish coming in a close joint 2nd.

If you want sparkle then go for Sparkle Mod Podge. I’d extend this advice for pretty much anything you want to add sparkle too, this is a great product for low mess glittering.

If you want your shells to remain matte I don’t think sealing is necessary at all. The matte products I tested out all worked well in that they coated the shells and didn’t change the colour or finish but I’m not sure there is any real benefit.

I’ve shared some more ideas for decorating these shells which I shared here: 2 easy ways to decorate plain shells, and they are now on display in a decorative bowl we have in our living room. I shall think of my auntie when I see them, I’m sure she would have approved.

Julie