Prep, prep , prep and more prep. Our sanding methods. Proper sanding promotes adhesion for the next coat. Excessive
sanding or using too coarse a grit can open pores in the surface or
create a sanding scratch profile too deep to be filled by the next
product to be applied. This can cause porosity holes in gelcoat and
sand scratch print–through. High Skill level is required. One professional sander is good for about 5 hours sanding per day.
All 5 types may be accomplished by hand, machine, block or blaster.The surface shape, size
and quality requirements will determine the tools or combination of
tools required.
1. Scratch Sanding: Scuffing or scratching a smooth surface to create
a profile to promote adhesion of another coating.
3M Scotch-Brite® Pads #’s 7447 or 7448 may be used to push
stripe edges down or remove light overspray from primer. Caution is
recommended when considering Scotch-Brite® for scratch sanding
between topcoats as adhesion will be questionable. Sandpaper is
recommended.
2. Smooth Sanding: Sanding the surface smooth of orange peel or
fine texture.
This is usually done with air tools, electric D8's, small blocks, small pad machine or hand
sanding using relatively fine grits. This type of sanding is not
considered fairing.
3. Block Sanding: Block sanding is used for fairing.
Block sanding by hand-board or machine is used to level a surface.
The depth and height of the highs and lows, and the width between
them, will determine the size block as well as the amount of
filler/surface products needed to fair the surface.
4. Grinding: Is for the removal of material. Grits are coarse, 24–36–60,
with the primary purpose being removal of undesirable material and
creating surface profile.
Grinding would be used to brighten corroded metal, remove old
coatings and to remove heavily oxidized or damaged gelcoat.
5. Sand blasting: the ultimate in protective coat adhesion and surface prep. Makes really bad surfaces like new again. Especially good for aluminum and steel boats but can also be applied to wood and fiberglass using different materials. Its starts for 30 ft boats at $10,000 for entire boat surface. Expenses in cleaning basting air, high cost of labor to blast, hard after job clean up and very dangerous. I would only use Greg Moore. No one else that smart would work so hard at get dirty.
Aluminum
Degrease with solvent or Sand Blast with 30-40 grit garnet
or Sand well using 60-120 grit
(aluminum compatible) paper. Clean thoroughly and
allow to dry. Prime using stronium as soon
as possible (within 8 hours) follow next day with epoxy primer
the finish the product
recommendations provided in the paint systems
guides.
Lead Keels
Degrease with solvent or blast with garnet shells or
Sand well using 120 grit
paper or power wire brush. Clean thoroughly
and allow to dry. Prime using an epoxy primer
following the product recommendations provided
in the paint systems guides.
Zinc/Galvanized Steel
Degrease with solvent or sand blast or
Sand well using 60-120 grit
(aluminum compatible) paper. Clean thoroughly and
allow to dry completely. Prime using an epoxy
primer following the product recommendations
provided in the paint systems guides.
Steel
Degrease with solvent. Grit blast to Sa 2.5 – near
white metal surface. If grit blasting is not possible,
grind the metal surface with 24-36 grit abrasive
discs to a uniform, clean, bright metal surface with
a 50-75 micron anchor pattern. Use angle grinder
on small areas. Clean thoroughly and allow to dry
completely. Prime using an epoxy primer then follow
the product recommendations provided in the final paint
systems guides.
Stainless Steel
Light grit blast to produce a profile of 50 microns,
clean thoroughly and allow to dry completely prior
to application of an epoxy primer then follow the
product recommendations provided in the final paint
systems guides.
Bronze
Clean thoroughly and abrade to bright metal using
80 grit paper. Take care when abrading bronze
propellers, as excessive abrading can alter the
profile of the propeller causing it to be out of balance.
Clean thoroughly and allow to dry completely before
applying products recommended for application
direct to bronze (see paint systems guides).
Cast Iron
Degrease with solvent. Grit blast to Sa 2.5. If grit
blasting is not possible, grind the metal surface with
24-36 grit abrasive discs to a uniform clean surface
with a 50-75 micron anchor pattern. Use an angle
grinder on small areas or a wire brush, prepare to
a minimum St.3 according to ISO8501-1. Clean
thoroughly with solvent and allow to dry completely.
Ensure that all evidence of corrosion (e.g. iron
oxide and iron sulphide) is removed prior to the
application of an epoxy primer then follow the
product recommendations provided in the final paint
systems guides.
Fiberglass
Degrease with solvent or Soda blast or
Sand well using 180-220
grit paper. Clean thoroughly and allow to dry
completely. Prime using an epoxy or one part then primer and finish
the product recommendations provided in the enamel or high gloss
systems guides.
Bare Wood/Plywood
Sand smooth with 80-180 grit paper and then 280
grit paper or walnut shell blast. Remove sanding dust by brushing or
dusting. Wipe down thoroughly with solvent and
allow to dry completely, to ensure any residual
sanding dust is removed, before applying products
recommended for application direct to wood
(see paint systems guides).
Oily woods e.g. teak
Ensure that the surface is thoroughly degreased
using a recommended solvent to ensure all oils
are removed. Sand smooth with 80-180 grit paper
and then 280 grit paper. Remove sanding dust
by wiping with solvent, to ensure any residual
dust is removed. Ensure the surface is completely
dry before applying products recommended for
application
Marine paint specs from proline a sherwin williams company. Proline Marine Paint technical Guide
For naval specs email email MIL spec paint questions to Greg Moore
SAND BLASTING MIl spec PDF download
