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Painting
PolyJet models takes half the time of other rapid prototypes. The
smooth surfaces and crisp details minimize the tedious and
time-consuming steps of sanding and filling. Since surface preparation
is the key to the quality of painted models, PolyJet delivers better
looking models in less time.
The supplies needed for your painting projects are inexpensive and are available at any hardware supply retailer.
Remove support material
The
key to a perfectly painted model is its preparation. This starts with
the removal of all support material. To optimize paint adherence and
cosmetic appeal, it is best to completely remove all support material
with the WaterJet station. Well-prepared models will have a consistent
feel on both supported and unsupported surfaces.
There
are two possible methods for obtaining a clean model surface. The first
option is to use a NaOH solution (2% diluted in water). To clean and
degrease the model, simply dip the model in the NaOH solution for 30 to
40 minutes, rinse with water and let dry. The second option is to bead
blast the model.
Sand surfaces
With
320-grit wet sandpaper, sand the model for a smooth, paint-ready
surface. While sanding, keep the sandpaper and model wet by repeatedly
dipping the sandpaper in water or placing the model under running
water.
With
the thin layers and fine detail of the PolyJet model, surfaces should
need only a light sanding. Following sanding, wash the model in water
and allow it to dry completely.
Apply primer
Primer
serves two purposes. Firstly, it provides a good bond coat for paint.
Secondly, it will highlight any areas on the model where additional
finishing may be needed.
Spray
the model with fast-drying primer. Lacquer-based primers and paints are
a good choice since they sand well, dry quickly and are readily
available. When priming or painting, use two light coats instead of one
heavy coat, to prevent drips and puddles. If you do not have a paint
sprayer, apply the primer from a spray can. Remember to spray the
primer in a well-ventilated area and wear appropriate safety equipment.
After the primer has dried to the touch, inspect the model for any areas that need additional sanding or repair.
Sand and fill blemishes
Depending
on the results of the primer coat, you can either proceed to the next
step or do some additional finishing work. Typically, if the primer is
applied correctly, no additional finishing is needed prior to applying
the finish paint. However, if there are blemishes in the primer coat
you may want to do some additional finish work. Finishing may include
wet-sanding and/or filling small pocks.
If
sanding is all you need, wet-sand the surfaces with 400-grit sandpaper.
Stop sanding if the PolyJet material begins to peek through the primer.
Rinse and dry the model. If any of the model surface is exposed, repeat
step three. Otherwise, proceed to step five.
Since the Eden
systems build with such small layers, you will not have to fill in
layer stair-stepping. However, if small blemishes show up in the primed
model, you can easily fill them with a dab of auto body putty. Body
putty comes in many forms, but you will want fast-curing, easily sanded
putty such as Freeman TUF-Carv. Alternatively, you can use premixed
glazing putty such as 3M™ Acryl-Blue.
After
the putty has dried – usually in less than 30 minutes – sand the area
smooth. Start with 220-grit sandpaper and finish with 400-grit
wet-sanding. Rinse the model with water and dry. Repeat step three.
Apply finish paint
Prior
to painting the model, ensure it is clean and dry. Use a tack cloth or
compressed air to remove dust. Apply several thin coats of finish
paint. Allow the paint to dry between each coat. As with the primer,
spray paint will do the job if you do not have a paint sprayer
available.
Apply clear coat (optional)
A coat of clear lacquer can be applied to provide additional protection against scratches, chips, and other marks.
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