Learn how to properly break-in your new Gruber Systems mold.

You have either purchased or about to purchase the finest mold available for cast polymer manufacturing. Learn how to properly care for your mold and ensure the longest possible life for your mold by following these instructions:

We want you to receive long, trouble-free use of your new mold. Please read these instructions carefully, and pass these instructions along to others in your shop that are responsible for any phase of work involving the use and care of this mold.


Mold Preparation

Upon receipt of your new mold, the first step is to carefully unpack and inspect the mold for damage in transit. Any damage should be reported immediately along with a freight claim to your common carrier, After inspection, the mold should be thoroughly cleaned with a mild detergent and water to remove grime, dirt, or any soap residue.

Do not clean this mold with any solvent as it will remove all preconditioning.

Prior to ordering a new mold, you should select the mold preparation and release procedure that best suits your operation and intended use of the mold:

Mold Type Recommended Mold Release System
Modular type molds requiring no set up or modifications and typically cast multiple times (i.e., modular vanities, shower pans, bathtubs, soap and shampoo holders, etc.) GruberCare™ MR (Multiple Release) GP Release System or HI-TEC.
Custom type molds generally requiring set up (no bowl vanities, floating bowls, large panels used primarily for custom set ups, etc.) GruberCare™ Release Wax System or MR GR
Solid Surface castings or any castings exceeding peak exotherm temperatures of 150° GruberCare™ MR Hi-Tec Release System

If you are unsure of which Release System to use or have a question, please call Gruber Systems at (661) 257-4060 for assistance.


Using the GruberCare™ Release Wax System for New Mold Break-in:

  1. Using a clean, lint-free cloth and an air hose, blow off and wipe the mold.

  2. Using a clean wax applicator sponge, apply the first coat of wax to the mold. NOTE: Ensure that all corners and side edges are coated first before proceeding to the deck areas. Wax should be applied in a circular motion, overlapping each pass by 30%. This will ensure good coverage of the mold.

  3. Allow wax to dry thoroughly to a haze (10 to 20 minutes).

  4. With a clean lint-free cloth, remove the wax by hand and polish to a high gloss. Turning the cloth frequently will help achieve this faster.

  5. Allow the wax to cure for a minimum of one (1) hour before applying the next coat. (Time dependent upon ambient temperature.)

  6. Repeat steps 1 through 5 five times. For best results allow the final coat to cure overnight before applying gelcoat.

  7. Apply a normal application of the gelcoat to the mold (20-25 mils). It is important that the gelcoat is gelling and curing as fast or faster than the Manufacturer's Data Sheet recommends on the gelcoat being used. This will reduce the amount of time that the styrene has to attack the surface of the new mold.

  8. After the gelcoat has cured to tack-free stage, use an air gun to blow the gelcoat lose from the mold surface. The gelcoat film should peel away from the mold easily. (We recommend that safety glasses be used during this process.)

  9. After removing the film from the mold, repeat steps 1 through 6 two more times.

  10. At this stage the mold is ready to be set up for production. Spray the mold with gelcoat and cast.

Notes:

  • If the gelcoat gel time and tack-free time are longer than the Manufacturer's Data Sheet references, consider not casting on the mold until corrections are made to ensure proper cure of the gelcoat.

  • It is recommended that during the set up of floating bowls and end stop dividers, that a smooth radius tool be used for applying either ExWax or clay to avoid scratching the mold surface. After tooling edges it is also recommended that a coat of wax be applied to the radius in order to smooth and re-coat the area that was touched by the radius tool.

  • The periodic use of GruberCare Interphase wax will reduce wax build-up and sometimes eliminate the need to remove the molds from production to be stripped and re-waxed due to wax build-up.

  • The use of wax over the Gruber MR System is recommended, but the Gruber MR System cannot be used over wax without proper stripping and sealing.


Using the GruberCare MR Series Mold Release System for New Mold Break-in:

  1. Using a clean, lint-free cloth and an air hose, blow off and wipe the mold.

  2. Using a clean, knit-type cotton cloth (Note: Do not use colored or dyed cloth), apply a wet film coat of Gruber MR Sealer to all edges and corners of the mold before proceeding to the deck area of the mold.

  3. Ensure that the mold surface is wet with sealer.

  4. Allow the sealer to set until evaporation starts. If there are any areas that do not evaporate, use a clean, lint-free cotton cloth to lightly wipe away the excess material, leaving a light film to evaporate.

  5. Coat larger molds by sections approximately 9 sq. ft. per section. This will allow you to work your way across the mold.

  6. Allow 15 minutes between coats to allow MR Sealer to cure.

  7. Repeat steps 3 through 6 three (3) times for a total of four (4) coats of MR Sealer.

  8. For optimum results, allow the MR System to cure for one (1) hour before application of MR GP or MR HI-TEC.

  9. Repeat steps 3 through 8 with either MR GP or MR HI-TEC. (See Notes for details.) Conduct a "tape test": Apply a strip of masking tape to the mold surface. Peel the tape away. It should peel easily. If not, repeat steps 3 through 6 with either MR GP or MR HI-TEC.

  10. For optimum results, allow the MR System to cure overnight.

  11. Apply a normal application of gelcoat to mold (20-25 mils). It is important that the gelcoat is gelling and curing as fast or faster than the times recommended on the Manufacturer's Data Sheet for the gelcoat being used. This will reduce the amount of time that the styrene has to attack the surface of the new mold.

  12. After the gelcoat has cured to a tack-free stage, remove the gelcoat from the mold using an air gun. It should peel away easily from the mold. (We recommend the use of safety glasses during this process.)

  13. After removing the gelcoat, repeat steps 3 through 6 with either MR GP or MR HI-TEC (See notes for details).

  14. At this stage the mold is ready to be set up for production and then to be sprayed with gelcoat and cast upon.

  15. The mold should be re-coated with MR GP or MR HI-TEC between each casting for the first 4-5 parts. This will build up a well-cured shell of release to ensure extended multiple releases.

  16. After the break-in period has passed, use MR Solvent Cleaner to remove wax, clay, and tape residue from molds as a daily cleaner.

Notes:
  • If the gelcoat gel time and tack-free time are longer than the Manufacturer's Data Sheet references, consider not casting on the mold until corrections are made to ensure proper cure of gelcoat.

  • The Gruber MR System cannot be applied over wax.

  • Gruber MR GP is recommended to be used on molds that require tooling, i.e., floating bowls, vanity decks, universal shower pans, custom set-up panels, etc. It is recommended that during the set-up of floating bowls and end stop dividers that a smooth radius tool be used to apply either ExWax or clay to avoid scratching the mold surface. After tooling edges, it is also recommended that a coat of wax be applied to the radius in order to smooth and re-coat the area that was touched the radius tool.

  • Gruber MR HI-TEC is recommended on modular type molds that require no tooling, i.e., integral bowls, tubs, splashes, and accessories.

  • Gruber MR HI-TEC is recommended for use in solid surface casting.


Note: GruberCare is a trademark of Marshall Gruber Company, LLC.