The two numbers
| Mark | What it is | Example from a maker |
|---|---|---|
| ECT | Edge crush test, a rating of how much top load a board's edge carries; a stacking-strength number | ECT-48, ECT-90, ECT-155 |
| Burst test (#) | Mullen burst rating in pounds, written 200#, 275# or 1,100# TW; an older way to rate board | 200#, 275#, 1,100# |
| Walls | Single, double or triple wall (TW) | SW, DW, TW |
| Maker and city | Who made the board, and where | Varies |
One distributor lists gaylords in single wall at 200#/ECT-32, double wall at 275#/ECT-48 and triple wall at 1,100#/ECT-90, across sizes from 36 x 36 x 36 to 48 x 40 x 36. An octagon-bottom triple wall of 46 x 38 x 36 is listed as ECT-155 with 1300# in its title; no load rating is stated, so treat 1300# as a product name. You can see how burst and ECT travel together on the first three lines.
How to read one on the dock
- Find it. The stamp is printed on a wall, often near the bottom or at a corner, in a circle or box.
- Read the walls. SW, DW or TW, or a count.
- Read the number. ECT, burst test, or both. Write them down.
- Compare. Use the wall-count ranges as a sanity check, not as a rating.
- Check the condition. A stamp on a damp, creased wall is a stamp for a box that is gone.
What the stamp does not tell you
It does not tell you the condition of the box now. A box that sat in a damp building has lost strength the stamp does not show. It does not tell you what the bottom will carry if it is partial and there is no slip sheet. And it does not make a used box UN-rated: a used box is not UN-rated unless certified. See UN-rated boxes.
Send us the stamp
A phone photo of the stamp is the quickest way to tell us what you have or what you want. We read it, confirm the wall count and tell you what the sellers' range suggests. See weight capacity and triple wall.
Facts and figures
- The Cary Company lists gaylords in single wall 200#/ECT-32, double wall 275#/ECT-48 and triple wall 1100#/ECT-90 across sizes from 36 x 36 x 36 to 48 x 40 x 36. (thecarycompany.com, retrieved 2026-11-10.)
- Uline lists its triple-wall 48 x 40 x 36 gaylord at 1,500 lb and its 36 x 36 x 36 at 1,200 lb. (uline.com, retrieved 2026-11-10.)
- ASTM D5168 covers the fabrication and closure of triple-wall corrugated containers. (Wikipedia, Bulk box, retrieved 2026-11-10.)
Terms
- ECT: Edge crush test, a rating of how much top load a board's edge carries; a stacking-strength number.
- burst test (#): Mullen burst rating in pounds, written as 200#, 275# or 1,100# TW; an older way to rate board.
- wall count: How many layers of corrugated board form the side walls, from 2 to 5; more walls, more stacking strength.
- triple wall (TW): Three layers of corrugated board; the classic heavy gaylord construction.
- pallet footprint: The box's length and width matched to a pallet, most often 48 x 40 in.
What to write down from a stamp
- The maker's name and, if shown, the plant.
- The ECT or burst figure, and which of the two the stamp gives.
- The gross weight limit and the box size limit if printed.
- The date or code, if any, and a photograph of the whole stamp.
Stamps that deserve a second look
- Faded, smudged or partly cut off stamps.
- A rating that does not match the wall count, such as a high figure on a thin board.
- Taped-over or painted-over stamps.