3M™ 8985L Anodizing Masking Tape

3M 8985L is a masking tape for anodising and surface treatment of metal parts. It protects areas that must not be treated: bores, seal faces, electrical contact surfaces, areas to be machined later.

Specifications

• Use: masking metal parts during anodising and surface treatment.
• Widths: 25 and 50 mm for routine masking, 305 and 610 mm for cutting and large surfaces.

Why a dedicated tape

A paint masking tape is not made to be immersed in a bath. In anodising, the part goes successively through degreasing, etching, the anodising bath and sealing. The tape must hold in each of these media without lifting at the edge.

The edge is what matters. If the bath seeps under the tape, even by a millimetre, the masked area is attacked and the part shows a halo that makes it non-compliant. An anodising tape is designed to keep a sealed edge throughout the cycle.

Successful masking

Degreased part. The tape is applied to a clean, dry surface after degreasing, otherwise the adhesive will not grip across the full width.

Edge pressed down. Press firmly along the edge with a spatula or fingernail to expel air and close off the path to the bath.

No creases. A crease forms a channel the bath can run through. On a shaped part, several overlapping pieces are better than one creased tape.

Removal after treatment. Remove the tape once the part has been rinsed and dried, pulling slowly.

For surface treatment shops

The wide 305 and 610 mm formats make it possible to cut masking templates for production runs, which speeds up preparation and makes masking repeatable from one part to the next.

See also our masking tapes, our polyester tapes and our 3M products.