Take a Partial Impression

Taking a partial impression reproduces one cross-section of your part when the removal constraint is too high for a complete impression. It drops the removal constraint close to zero and lets you use Medium and Rigid products.

When a Partial Impression Is the Right Choice

A partial impression reproduces one cross-section of the shape instead of the whole cavity. Use it whenever you need a profile or a surface finish and not a diameter or a radius. This applies even when the removal constraint is normal. You can also use it when the removal constraint is too high for every product of the range. It saves product too, as a half impression uses half the material of a complete impression.

Why It Works

With this method, the product no longer has to pass through a narrowing to come out. The removal constraint drops to zero or close to it. Medium and Rigid products become usable, so you can slice the impression or measure it with contact.

Step by Step

1. Identify the useful zone: a profile, a surface finish, or a local area, not a full diameter.
2. Orient the part to expose only the half section you need.
3. Lay Plastin as a clean barrier to bound the application area and stop the product from running.
4. Apply the product. Prefer a Pasty or a Manual Putty product, P35 or M70, for a precise placement.
5. Compress lightly so the product touches the whole surface of interest.
6. Let it polymerize, then pull it straight off.
7. Measure the impression on a profile projector or a vision system.

Related Pages

• Removal Constraint
• Temporary Void and Reinjection
• Plastin: Four Uses
• Re-Form: Holding, Protecting and Impression Templates