Material, or appearance? — gull system handbook

Material moves the mass, the cut list and the title block. Appearance moves only the picture. How to tell which one you need.

Material, or appearance?

Material moves the mass, the cut list and the title block. Appearance moves nothing but the picture. Confusing them means shipping a part that looks right and carries the wrong numbers.

They are captured with the same gesture and set up the same way, which is why they get confused. The difference is what the customer's choice changes on paper.

• Material is a physical fact. When a customer picks stainless instead of structural steel, the density changes — and with it the part's mass, the cut list and the figures in the drawing's title block. Those are the numbers you quote and manufacture from.
• Appearance is only a colour or a texture. When a customer picks red, nothing changes but the picture. No number on the order moves.

How to tell which one you need

1. Ask whether the customer's choice should move a number — the mass, a cut-list entry, a title-block figure. If it should, it is material.
2. If nothing but the picture should move, it is appearance.
3. If both — painted steel in a colour — capture both parameters. They are separate, and each has its own rule.

Where each one is captured

• Material. on a part only.
• Appearance. on a part or on a single body, so on a weldment you can colour one body and leave the rest alone.

Merging them would show up in your library. Powder-coated steel is one material and twenty colours. If an entry always carried both, the library would need every combination — twenty entries instead of one material and twenty colours.

That does not mean the customer has to choose twice. A single entry can carry both a material and a colour, with one input driving them together. How to wire that is in Wire a finish to the customer's choices.

⚠ There is one connection between them: a CAD material brings its own appearance with it. gull system handles that for you, but it is worth knowing why — see Silent material failures.