Bubbles or Voids in the Impression
Bubbles are air trapped during the injection. Either the tip came out of the product, the injection was too fast, or the nozzle was not in contact with the surface.
A bubble in the measurement zone means making a new impression. You treat a defect by finding its cause, never by adjusting the measurement.
Fluid Product in a Cavity
- Clip a tip on the nozzle.
- Start at the bottom of the cavity.
- Keep the tip immersed in the product for the whole injection.
- Rub the walls in small circles to release the bubbles held against the surface.
- Fill slowly. A fast injection folds air into the product.
Pasty Product on a Surface
- Work without a tip.
- Keep the nozzle in permanent contact with the surface.
- Inject with slight pressure so the product enters the details.
- Compress the product with a flat card.
Very Small Bores
Use a needle nozzle or a Luer Lock nozzle with a Fluid product. If a bubble stays stuck at the bottom, insert a Fill’in and stir gently in circles to free it.
Large Volumes
With an XL product, pour from the lowest point in a thin stream and let the product rise. Bubbles are harder to eliminate in a large volume, so take your time.
Two Other Causes
When the surface is greasy, the impression can separate from it during polymerization, which creates voids. Degrease with DN1 before every impression.
To clear air from the nozzle, extrude until a homogeneous drop appears before you inject.
