Quality
Tolerances in hand casting: what is normal and what is a defect
How much dimensional variation is normal in hand-cast bronze, which surface marks are acceptable, and how to write an inspection standard your supplier can actually meet.
Every hand-cast piece is slightly different. A buying contract that pretends otherwise creates arguments instead of preventing them; a contract that states real numbers protects both sides.
Dimensional variation
Our published figures, which are typical of solid cast work at this scale:
- ±1–3 cm across a five-piece set is normal.
- More than 5 cm on a single piece is a fault. We re-cast it.
- Proportion within a set matters more than any absolute figure: cranes 5–7 cm taller than the censer, candlesticks 12–15 cm shorter.
Note also that a trade size is not a measurement. A censer sold as “60” is made from the 60 pattern and measures about 57 cm. Ask for measured heights for your catalogue, or your customer will measure it for you.
Surface: what is character and what is a defect
- Acceptable: faint file marks under the patina in areas not visible in normal display; slight variation in patina depth across a large surface; small differences in the depth of chasing between two castings of the same piece.
- Not acceptable: cold shuts (where the metal failed to fuse, visible as a seam or a wrinkle), porosity breaking the surface, cracks, a casting that rocks on a flat table, patina that rubs off on a dry cloth.
Weight as a specification
Ask for the cast weight and put it on the order with a tolerance — ±5 % is reasonable. Weight is the one specification that cannot be faked with a finish, and a piece 20 % lighter than the sample you approved is a different product.
Writing an inspection standard that works
- Approve a physical sample and keep it. It is the reference, not the photographs.
- State measured dimensions with tolerance, cast weight with tolerance, and the finish by sample number.
- List defects that cause rejection in plain words, as above.
- Agree the remedy in advance: re-cast, credit, or discount. Shipping a heavy casting back across an ocean should not be anyone's plan.
- Agree how faults are evidenced: photographs of the piece as received, with the carton, within a stated number of days.
Why a foundry publishes this at all
Because the alternative is a conversation after your container lands, when both sides are working from memory and one of them has already sold the goods. A supplier who will not state tolerances in writing is not being flexible; they are keeping their options open at your expense.