Composite Release Agents

In composites molding, "mold release systems" refer to products used in tandem to properly prepare a composite tool and release the part with desired surface characteristics. Release systems typically include: 

1. A mold cleaner
2. A mold primer or sealer to eliminate porosity and protect molds 
3. A release agent to aid part removal

For large, highly expensive parts, the mold may be stripped and recoated with a sealer and release agent before each part is produced. In other cases, the sealer will typically last for multiple parts and molders need only apply a thin release agent layer over the sealer. In some cases, multiple coatings of release agent can be applied to act as a sealer, and a single coating of the release is applied before each part.

Eventually, sealed molds will need to be stripped and recoated to ensure release and part quality.

Consult the product TDS for application instructions and carefully follow instructions to ensure part quality and release.  

Mold sealers are used in tandem with release agents (and mold cleaners) to produce composite parts, particularly when a high-quality finish is required.

Mold sealers must be carefully chosen and applied to ensure material compatibility and proper performance.

Mold sealers are applied to clean molds before a release agents to seal microporosities. Sealing microporosities keeps resins, binders, and contaminants from working into the surface of molds which will negatively impact release and part appearance. The most sealer also creates a surface that is more conducive to release agent bonding, improving the performance of the release agent. 

Follow all safety precautions when cleaning a mold and ensure proper personal protective (PPE) equipment is worn at all times.  

Start by removing any buildup on the mold surface. Use the least abrasive methods possible to avoid damaging the mold surface. Selecting the right cleaning agent or solvent can reduce the amount of physical abrasion (and effort) required to clean your mold. Click here to learn more about our mold cleaners and industrial cleaners. If available, use compressed air to remove residues loosened by the cleaner or left over from mechanical scrubbing. Some molders may find it necessary to bead blast molds to remove tenacious residues.

Wipe the mold clean with a lint-free towel after all residues have been removed. It may be beneficial to rinse molds with clean water/ or a mold solvent to ensure all debris is removed. Ensure the mold is dry before application of release agent. If your mold will not be used or stored after cleaning, it is often beneficial to apply your release agent to the mold to protect it during downtime. Consult the release agent TDS or contact McLube® for more information about mold protective coatings.  

Other Tips:

• AVIOD using synthetic cloths which may be degraded by solvent-based release agents and cleaners. NEVER reuse cloths. 
• Conduct a tape test to determine if the mold is properly prepared and ready for release agent application. Learn about conducting a tape test. 
• After applying a mold cleaner or suitable cleaning solvent, it is often beneficial to let the cleaning agent sit on the mold surface for a period of time to break down residues before scrubbing.
• Mold cleaning can be a time consuming and expensive process. If your molding line experiences excessive downtime for cleaning, it may be beneficial to consider a different release agent or application method. Overapplication or improper cure of semi-permanent release coatings are common issues which leads to extra downtime for cleaning. In many cases, molders using sacrificial release agents can cut down on downtime due to cleaning by switching to a semi-permanent mold release agent.
• During mold cleaning downtime, also clean dilution equipment (if applicable) as well as your application equipment.  

In most cases, this is a result of improper mold preparation. Conduct a tape test after cleaning your mold to ensure it is ready to receive the sealer/ release. Carefully follow application instructions for sealers and release agents. If certain areas are more prone to rub marks or diminished surface appearance, consider additional release agent touchups in these areas. 

The most common confounding factors in a release agent trial are: 

1. Prior coatings on the mold surface/ test surface is not cleaned before trial
2. Release agent was not properly mixed before use (if applicable)
3. Improper application method
4. Dilution ratio is too high/ low

READ AND UNDERSTAND the safety data sheet for a new chemical material before use, handling, or other disposition. 

Ask your McLube product specialist for help selecting the appropriate release agent for your application. Share as much information as possible to guide product selection.

When preparing to evaluate a new release agent, we recommend thoroughly cleaning the mold surface before running the trial. Use a suitable cleaning solvent or mold cleaner to ensure the surface is properly prepared. Prior coatings, resin buildup, debris, etc. can affect the performance of the new release agent. Conduct a tape test on all areas of the mold to ensure it is clean; the tape should adhere. A tape test should be used to verify the surface is properly prepared. Learn how to perform a tape test here. 

Ensure the equipment used to conduct the test is also clean, free of any other coatings or contaminants. 

If the release agent must be mixed before use, ensure all solid, active ingredients are redispersed from the bottom of the container before running trials. 

Consult the release agent's TDS and your McLube Technical Sales specialist for tailored application instructions for your process. Carefully follow application instructions for the new release agent, especially if you trialing a semi-permanent release coating for the first time that requires specific curing conditions. For semi-permanent coatings, conduct a tape test to ensure the release agent is properly applied and cured; the tape should not adhere, or not adhere as well as it did on the clean mold surface.

NOTE: Many molders experience poor results with a new release agent because they do not properly apply the release agent, or use an application method recommended for a different coating. Different mold release agents may require different application methods to achieve the desired results. 

Test the release agent in a lab setting first, if possible. Following success, select a test mold or tool that best reflects your actual process conditions. Document the trial to be sure results can be repeated. Consider having the trials conducted by the actual mold operator. 

If your material, process, application method, or dilution ratio (if applicable) changes, retest the release agent to ensure the changes will not affect release performance and lead to molding issues on the line. 

When a release agent is suitable for dilution before use, consult the product TDS and your McLube product specialist for recommended starting dilution ratios for your process. Begin trials at the starting dilution ratio and achieve success before attempting further dilution. Ensure dilution equipment is clean and free of contaminants or other coatings.  

McLube product specialists are available to conduct testing with you at your facility. Molders may also send a sample of their materials to McLube for initial tests before sampling.