How to Decorate Envelopes with Rubber Stamps: Sardine Fish Stamp Ideas | CassaStamps

There is something quietly wonderful about a decorated envelope arriving in a mailbox. Before the recipient even opens it, they already know something handmade and thoughtful is waiting inside. That is the magic of mail art — and rubber stamps make it effortless.

In this post I want to share one of my favourite recent ideas: using my hand carved sardine fish rubber stamp to turn plain kraft envelopes and gift bags into something you would actually want to frame. Whether you are a journaler, a snail mail enthusiast, or someone who loves adding a handmade touch to their packaging, this technique is surprisingly fast and endlessly satisfying.

Why Sardines? The Story Behind the Design

I live in Barcelona — a city where the sea is never far from your imagination. The sardine is deeply embedded in Mediterranean culture, appearing in everything from fishing nets to ceramic tiles to summer festivals. When I carved this stamp, I wanted to capture both the elegance of the fish's silhouette and the lively, slightly chaotic energy of a school of fish moving together.

What I did not expect was how incredibly versatile this stamp would turn out to be. A single sardine on a gift tag. A scattered school across wrapping paper. A repeating pattern all over an envelope. Three sizes working together in a layered composition. The same carved image produces a completely different feeling depending on how you use it.

What You Will Need

• A sardine rubber stamp (or any fish / marine stamp)
  I used my sardine stamps in two different sizes — having multiple scales makes the compositions much more dynamic.
• A black ink pad
  I use a standard pigment ink pad. Black gives the crispest contrast on kraft paper and has that classic linocut look.
• Kraft envelopes or paper bags
  Kraft paper is the best surface for this — it is porous enough to absorb the ink cleanly and the warm brown tone makes the black impressions feel like a vintage botanical print. The silver color would be a plus for this project.
• Plain white card stock for tags
  White tags with a single smaller fish stamp make the perfect label for a gift or a snail mail envelope. I used my articulated fish stamp for the tags.
• A baby wipe
  For cleaning your stamp between uses — no need for complicated stamp cleaners.

Three Ways to Use a Sardine Stamp on Envelopes

1. The all-over pattern envelope

This is the most striking result and also the simplest to achieve. Take your largest sardine stamp, ink it thoroughly, and begin stamping in a loose diagonal pattern across the entire front of the envelope. Vary the angle of each impression slightly — some pointing left, some right, some slightly tilted — to mimic the natural movement of a school of fish. Do not overthink placement. The beauty of hand stamping is that slight variations in pressure and alignment add character, not mistakes.

2. The single stamp gift tag

Cut white card stock into small rectangular or luggage-tag shapes and use the smallest stamp from the set. One clean, centred fish impression on a white tag, a hole punch at the top, a brass brad or piece of twine — and you have a gift tag that looks like it came from a high-end stationery shop. This technique also works beautifully on the back flap of a plain envelope as a personal seal.

3. Mixed-size layered composition

This is my favourite and the one you can see in the photograph above. Use all three sizes together on a single piece — large fish stamped in the background, medium fish layered over them at different angles, and the smallest fish tucked into the gaps. The result has the feeling of a lino print or a vintage natural history illustration. It takes a little more time but is deeply satisfying to make.

Ideas Beyond Envelopes

Once you have a marine rubber stamp in your collection, the possibilities really do not stop at envelopes. Here are some of the things I have seen customers make — and that I love trying myself:

A Note on Ink and Paper

The most common question I get is: what ink should I use? For paper and envelopes, any water-based pigment ink pad in black will give you crisp, archival results. For fabric, you need a fabric-specific ink pad — the most popular are Ranger Distress Oxide or Versacraft — followed by heat-setting with an iron through a cloth. For darker papers, you can try white or gold ink for a completely different effect.

Kraft paper is genuinely the most forgiving surface to stamp on. The texture absorbs ink beautifully, slight imperfections feel intentional, and the warm brown tone gives every stamped impression a warm, artisanal quality that glossy white paper simply cannot replicate.

The Joy of Handmade Mail

We live in a world where nearly every message arrives as a notification on a glass screen. A handmade, stamped envelope takes thirty seconds longer to make than a plain one — and it is remembered for weeks. There is a whole community of people who collect and photograph the envelopes they receive; snail mail art is a genuine social phenomenon with a dedicated and passionate following on Instagram and Pinterest.

Rubber stamps make it accessible to everyone. You do not need to be able to draw. You do not need an expensive setup. You need a stamp, an ink pad, and five minutes. And the results look like something that took an hour.