COMPOSITE MOLD RESURFA RESURFACING CING WITH DURATEC® AND AQUA-BUFF® PRODUCTS
Hawkeye Industries Inc.
When to resurface? A business decision.
High quality molds produce high quality parts and result in less rework. Mold resurfacing is a realistic option to mold replacement when the mold is structurally sound and only the gelcoat surface has deteriorated. d eteriorated. Resurfacing mold is a lower lower cost option and allows the full value to be extracted to the mold. Estimated material cost to resurface is $1.50 per square foot, compared to an estimated $14.00 per square foot for mold replacement, a savings of 89%.
Repair vs. Resurfacing
Chips, cracks and gouges on otherwise sound molds can be repaired with Duratec Mold Repair Putty, sanded and polished to a flawless surface. If however, a mold has numerous defects and an overall dull and rough finish, resurfacing is the appropriate appropriate course of action.
Duratec® and Aqua-Buff ® Products for Polyester and VE Mold Resurfacing Duratec Vinyl Ester Mold Repair Putty (if needed) Duratec Polyester Surfacing Primer Duratec Vinyl Ester Hi-Gloss Topcoat Duratec Thinner Aqua-Buff Tuff-Stuff® Rapid Cut Compound Aqua-Buff GlossMaster® Polish
Prepping the Mold
The surface should be clean, dry and free from oil, grease, wax or other contaminants. Ambient temperatures should be in excess of 60°F, 16°C to ensure a rapid and complete cure. Time calculations are based on temperatures of 77°F, 25°C. Prior to sanding the surface all mold releases must be removed using the chemical stripper recommended by the mold release manufacturer.
Prepping the mold Starting from a correctly shaped and dimensionally stable mold, sand the entire surface with a coarse sandpaper (80- or 120-grit), making sure to feather in puttied and filled areas.
Prepping the mold Wipe the sanded surface with acetone and a clean white towel. Do not use a tack rag.
Product preparation Thoroughly stir Duratec Polyester Surfacing Primer prior to catalyzing. Due to the rapid gel time of the primer, mix only the amount that can be applied within 16-18 minutes @77°F, 25°C. (Higher temperatures yield a shorter pot life and gel time, while lower temperatures yield a longer pot life and gel time.)
Product preparation Catalyze at 2 percent with mekP catalyst (20 cc per quart). The primer can be thinned up to 10 percent if necessary to achieve a fine spray. Thin with Duratec Thinner or Methyl Ethyl Ketone solvent after catalyzation.
Spraying the mold We recommend a gravityfeed, siphon or pressure pot system with a 2.5 millimeter tip and 38-42 psi of line pressure (12-15 psi in a pressure pot). Apply a "tack coat" to the entire surface and allow it to flash for 2 minutes.
Spraying the mold Follow with wet passes, slowly building to the desired thickness of 15 mils (375 microns) unless the surface is unusually rough and requires a greater build.
Spraying the mold Heavier thickness can be achieved by repeating the process immediately after gel has occurred.
Allowing the mold to dry The primer will be dry to the touch in 1-4 hours, depending on thickness and temperature, and ready to sand within 2-4 hours at 77°F, 25°C.
Sanding the mold Dry sand the entire surface with 80- or 120-grit sandpaper.
Cleaning the mold Wipe the surface with acetone and a clean white cloth. Do not use a tack rag.
Topcoating the mold To achieve the ultimate gloss and surface durability apply Duratec Vinyl Ester Hi-Gloss Coating.
Product Preparation Thoroughly stir Duratec Polyester Hi-Gloss Coating prior to catalyzing. Due to the rapid gel time of the coating, mix only the amount―less than a quart―that can be applied within 15-18 minutes. (Higher temperatures yield a short pot life and gel time while lower temperatures yield a longer pot lie and gel time.)
Product Preparation Catalyze at 2 percent with low hydrogen peroxide mekP catalyst (20 cc per quart). Thin after catalyzing with Duratec Thinner if needed to create a fine spray.
Spraying the topcoat We recommend a gravityfeed, siphon or pressure pot spray system with a 1.8 millimeter tip and 38-42 psi of line pressure (12-15 psi with pressure pot). (This work was done with a Binks M1G cup gun and a 2.2 millimeter tip at 40 pounds of line pressure.)
Spraying the topcoat Apply a "tack coat" to the entire surface and allow it to flash for 2 minutes. Follow with a mist coat and two-three wet passes to achieve a thickness of 1520 mils, 375-500 microns, over the sanded surface.
Curing the topcoat Allow the topcoat to cure to a “dry-to-the-touch” condition (4-8 hours at 77°F, 25°C). If properly applied there will be very little orange peel or dry overspray. The topcoat must be sanded and polished to achieve full cure and best performance.
Sanding the topcoat When the topcoat has cured, begin with the finest sandpaper that will take down the surface profile and sand the surface, working through the grits, up to 1000grit paper. Note: For best results, after sanding, wait at least overnight at 77°F, 25°C before compounding and polishing the surface. For exceptionally large molds that require two days or more days of sanding, no waiting is necessary.
Compounding the mold Remove scratches with Aqua-Buff Tuff-Stuff Rapid Cut Compound. We recommend an industrial style buffer, operating at 2200 rpm.
Compounding the mold Apply Tuff-Stuff in three (3) quarter-size mounds per square foot to the mold surface. (If the compound builds up on the pad reduce the amount applied.)
Compounding the mold Using a professional buffer, buff with a wool or wool-blend compounding pad. The surface should look wet. If not, apply more TuffStuff.
Compounding the mold Buffing speeds will vary depending on individual buffing styles, but buffing at too high of a speed (greater than 2200 rpm) can cause surface burning.
Compounding the mold Buff the surface with Tuff-Stuff until the haze is eliminated and all sanding scratches are removed.
Polishing the mold Polish the mold with Aqua-Buff GlossMaster Polish.
Polishing the mold Application — Apply GlossMaster in three (3) quarter-size mounds per square foot to the surface that is to be polished. (If the polish builds up on the pad, reduce the amount applied.)
Polishing the mold Using a professional buffer, polish with a soft polishing pad.
Polishing the mold While polishing, the surface should look wet. If not, add more GlossMaster. Polishing speeds will vary depending on polishing styles, but we have found that speeds of 2400 rpm work well.
Polishing the mold To obtain the highest possible gloss finish, you may follow with an egg-crate foam polishing pad. You will want to use a water mister bottle to keep the surface wet.
Polishing the mold Polish until the haze is eliminated and you have a smooth, glossy finish.
