Finishing SLA

Priming SLA

It is advisable to spray a thin base-coat on the prototype part before sanding Give the part an even colour, reveal the

unevenness, holes, cracks and other surface defects which are difficult to spot

Act as a marker so that in subsequent sanding, it is easy to visualise which areas had been sanded

Reveal contaminations such as uncured resin on the part

Can Spray Demonstration

Sanding

Sandpaper is a form of paper where an abrasive material has been fixed to its surface; it is part of the "coated abrasives" family of abrasive products

Used to remove small amounts of material from surfaces, either to make them smoother (painting and wood finishing), to remove a layer of material (e.g. old paint), or sometimes to make the surface rougher (e.g. as a preparation to gluing)

Waterproof or wet/dry sandpapers use a resin bond and a waterproof backing

Adapted from: http://en.wikipedia.org/wiki/Sandpaper

Grit Size

Grit size refers to the size of the particles of abrading materials embedded in the sandpaper

ISO 6344 is an international standard covering the materials sizes and tests regarding sandpaper and other similar coated abrasives. It has three parts: ISO 6344-1:1998: Coated

abrasives, sizes and tests ISO 6344-2:1998: Macrogrit,

P12 to P220 ISO 6344-3:1998: Microgrit,

P240 to P2500

Grit Designation

ISO/FEPA Grit designation Average particle diameter

Material removal P60 0.269 mm

P80 0.201 mm

Sanding finishes P100 0.162 mm

P120 0.125 mm

Final sanding before painting P150 0.1 mm

P180 0.082 mm

P220 0.068 mm

Sanding finishes between paint coats P240 58.5 µm

P360 40.5 µm

P400 35 µm

P600 25.8 µm

P800 21.8 µm

Finishes before buffing

P1000 18.3 µm

P1200 15.3 µm

P1500 12.6 µm

Final sanding before buffing P2000 10.3 µm

P2500 8.4 µm

Material removal

Use #60 to #100 for material removal

Use a rigid sanding block whenever possible

Wrap the paper around half-round or round sanding-block to shape concave surfaces

Dry or wet sand Use the hand to feel the

surfaces

Face by faceFrom large face to smallFrom flat face to pronounceKeep small protrusion and fillets

untouched

Use chisels to clean negative sharp corners

Sanding finishes

Change to #200 - #400 paper

The base-coat will be removed gradually to reveal body material

The target is to ‘replace’ previous coarse sandpaper strokes with finer strokes

The progress will be fast at the beginning and will slow down when the surf

Progressive Sanding

A: Thoroughly sanded away all previous strokes

B: Leave a trace of previous strokes

C: Change sandpaper pre-maturely

D: Use finish sanding to ratify unevenness of C

A

B

C

D

Spray Painting

AdjustmentCleaning before sprayTypes of paintPaint mixingSequencing the strokesSpraying direction and movementCleaning after sprayDrying