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Japanese Glass Fishing Floats

Updated: Feb 12

Anyone else obsessed with Japanese glass fishing floats like me?

I have been lucky enough to find just one on my beach here (actually, two but the first one was right after the 2011 tsunami...another story for another time...).  I do from time to time, find the seals where they are often called in the west “mermaid nipples”.

This is my favorite find - a super chunky frosty float seal.

My guess is that it came from a 10” float.

So a little history about these. These were made from recycled glass.  In a discussion with the last remaining glass float blower in Japan who is located up north in Hokkaido, he explained that glass floats were never made directly from sand but always with recycled glass. They would break sake bottles, ramune, Coca Cola bottles, shoyu and other glass materials which would be melted down and shaped into a sphere.  Due to the mixture of these colored bottles,  the result was the blue/green color which dominates the glass fishing floats.  Of course there are other colors like brown which came from beer bottles and even more rare colors like cobalt, purple, red and orange that came from excess glass from glass factories making high end products.  

Japan calls these floats ukidama or bindama which simply translates to "buoy ball" or "glass bottle ball".

Japan started using glass floats as early as 1910 - although they were not the first to create them. In fact, it was Norway back in 1840 who first produced them. However, once Japan jumped on board with its massive deep sea fishing industry, they soon became the leader in production.

Prior to glass being used for floats, wooden floats were used. They were made with paulownia wood which is light weight and buoyant.  However they were causing problems with durability and buoyancy so an alternative solution was needed. One fishermen explained to me that for every 3 wooden floats attached to netting only one glass float was needed so glass turned out to be far more efficient and cost effective.

By 1915, small glass floats were mass produced and soon operations opened up throughout Japan.

What started as a 3 inch float was soon adapted into other sizes which related to the fishing gear and types of fish caught. Sizes range from 1.5 inches to 18 inches. This photo shows my collection which unfortunately is missing an 18 inch  - the largest one there is a 17 inch float. 


The smaller size floats were used for gill nets, octopus lines and crab nets.  Trout, sardines, shad, and larger fish such as salmon were also caught with the aid of this size. 

The medium size was used for gill nets, trawl nets and to make stationery traps and long lines for tuna.

The larger sizes were used for teichiami “stationery nets”, marker buoys, jig fisheries and long lining. This was especially used in deep seas.

Endosan, our good friend and fisherman neighbour, explained to me that in deep sea fishing for tuna where the larger floats are used, typically 1000 floats would be taken out together. That’s just for one trip! So you can see why many would be produced but also how many would get lost out in sea and wash ashore as a whole or broken up making them perfect for sea glass. 

Now one of the first things avid collectors of floats look for is the seal mark.  These seal marks can tell us a lot about where it came from, how old it is, who used and if it is rare or common.  These marks were used to identify the float or trademark.  It must be noted that not every float has a seal mark on it as it was usually done by large companies and are symbol of the glass factory that made them.  So for example, the local glassblower that was in this town, who sadly is no longer with us, he did not place a mark on the floats for the local fishermen here.  

For those that were marked, they usually came in the character of the first syllable of the name of the company.  

A very quick lesson in Japanese language - there are 3 written forms: kanji, katakana and Hiragana.  And yes, as a newbie in Japan learning Japanese, this completely messed with my brain at first.  But basically kanji is the pictograph borrowed from Chinese, katakana is phonetic and is words and names of foreign origin (for instance my name) and Hiragana is also phonetic and basically covers everything else that kanji and katakana does not cover.

Very basic linguistics lesson completed. 

So back to floats, there are hundreds of marks but there were just a few factories that dominated with their marks particularly post war.

Half of my floats do not have a mark but here are just a few that do have the common marks:

1. "Sen"  - Written in kanji and comes from Sendai Glass Factory. Sendai is the main city where I live close to so these are extra special to me.

2. "Kita" - written in Kanji and means "north" 

3. "Se" - Written in katakana and believed to be the mark of the Otaru Glass Company 

4. Maruha  - Written in Hiragana. From Maruha Fishing company which is still active.

5. Bestu - Written in Kanji which is a place in Hokkaido.

There is lots of information on the marks out there thanks to Amos Wood and Walt Pich so be sure to check out their materials for more in depth information if you have not already done so.

One thing I love with fishing floats are the bubbles and swirls and streaks which I often find in sea glass . Were they deliberately created this way? No. Simply it is a flaw as they wanted to move as quickly and cheaply as possible in production so the materials were not properly cleaned in between each one produced hence the mixture of colors from the recycled glass.

Another feature I love about fishing floats are the nets that connect and protect the glass.

I asked around to find out if there was a standard design for the nets or if certain designs had a specific purpose. Each fisherman in this area simply said that it was just up to the fisherman and whatever they preferred.  Sometimes the netting would help identify whose floats they belonged to.

Very old ones used natural fibers like hemp and were hand knotted. Newer ones from the late 50s used polypropylene which proved to be more durable.

So that is a brief insight into Japanese Fishing Floats!

Like any of the photos in this post? Some (and more!) are available in Digital Prints in my store!


Please note, I do not sell floats on behalf of other people. If you wish to sell your float, I recommend visiting the "Glass Floats Deal or No Deal" Facebook Page.

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I knew nothing of these floats. Thank you so very much for the information and the obvious care with witch the article was written. Your love of the floats and thier history comes through with your words. Thank you.


Great information! Thanks for sharing!


I wish I still had mine. My EX did something with them along with everything else I had

Replying to

I totally get the he did something with it. Going thru this right now . I had HAD roughly 400 decir eggs not like easter but just paper weights etc. Ya I found five n all were broken . Men ..

Any ways brings me to my float. I have had it about twenty years and am gonna look n see how real it is ... I have to repair the net or make a new . . Came here to learn but haven't found any net I like yet!!! Good day!!!

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