Q: I was wondering if you could help me locate a supplier of double walled boxes, I need them for packing up my goods and shipping them back home. I have been told by the shipping company that regular single walled boxes (like the ones you find with goods stacked in them, e.g. washing powder), are not strong enough to endure shipping. So far I have only found single-walled boxes at my supermarkets and 100 Yen stores.
A: After a bit of searching, I learned that Japan classifies their boxes by size and also with letters depending on the thickness of the box and the fluting of the corrugated fiberboard between the box walls.
For anyone who may not know, a typical cardboard box used for shipping and transport is called "danbo-ru" (ダンボール) in Japanese. You might also see it as 段ボール or ダンボール箱 (箱 is "hako" or box).
There are different classifications of the box, depending on the fluting mentioned above. I believe this is similar in the US, but I'm not sure about other countries, so feel free to share what you know. Anyway, they're usually indicated with a letter and "flute" in English or "フルート" in Japanese. A, B, C, E, F and G, seem to be most common, although it varies (sometimes they are only noted by the thickness in mm rather than the type of fluting/thickness).
Double-walled boxes are basically if you took the walls of two regular boxes and glued them together (hence, double walls...). These are called Wフルート, or you may also see it as W段. Otherwise, the thickness of a double-walled box is around 8mm, so if you find a box that wide, it's most likely double-walled.
I was able to find double-walled boxes on the following sites (Japanese only), but if you know of any other resources to add, please let us know!
Corrugated Goods Craft
Office Depot (x2)