Motorsport Composite Fundamentals: Release Agents

Back to course

Watch This Course

$199 USD

-OR-

Or 8 easy payments of only $24.88 USD Instant access. Easy checkout. No fees. Learn more

Enroll Now
8 easy payments of only $24.88 USD

Course Access for Life

60 day money back guarantee

Release Agents

07.57

00:00	The various forms of mould release agents are required to prevent materials bonding to the mould surface, essentially allowing us to remove our parts from the mould after curing with as little effort as possible.
00:12	This not only makes our lives easier and the project more efficient, but also prevents the risk of damaging the part or mould by overstressing it.
00:21	As you might have guessed, these agents are also used for the same reason during the construction of a mould to prevent it from sticking to the pattern or plug.
00:30	The agents are applied to the mould or pattern surfaces prior to anything else including gel coat, reinforcement and the resin system.
00:38	There are a few preparation steps required before the release agent can be applied though.
00:43	First, we need to ensure the mould is perfectly clean and this means the use of a solvent mould cleaner.
00:49	Something like isopropyl alcohol or wax and grease remover will work well here without damaging the mould surface or dedicated cleaners for composite tooling often contain a combination of solvents.
01:01	These will remove any dirt, grease or other contaminants like previously used release agents and waxes so we're ready for our new release agents.
01:10	The next preparation step isn't actually required in every case and that's the use of a mould sealer.
01:16	This is only required to seal the surface on moulds made using model or tooling board as well as other porous materials which is going to ensure it won't absorb any of the release agent or other substances.
01:28	It is recommended to apply a sealer to new moulds regardless of the material for good measure though.
01:33	The sealer is either applied by hand or sprayed on in multiple layers and then finished with some light sanding for a smooth and even finish.
01:41	It can also be used to restore the surface finish on used composite moulds particularly for those that haven't been gel coated.
01:48	Once sealed we're ready for the release agent.
01:51	Like most things we've covered in this course so far there are plenty of products on the market.
01:56	A lot are very similar and others are designed to work with a certain composite material.
02:01	The traditional approach is a mould release wax which come in a very malleable solid form at ambient temperatures like the car wax we're probably all familiar with and just like car waxes there's also spray on options.
02:15	Either way these waxes are applied to the mould surface with a clean rag or application pad allowed to stand for five to ten minutes for the wax to haze up and then they're buffed off.
02:26	We'd typically build up about five to eight layers for a high gloss release barrier reapplying between pulls as needed.
02:33	These waxes are usually based on a carnauba wax due to its higher heat resistance compared to the alternative of paraffin wax.
02:41	However, their service temperature is the main limitation and they often can't be used if we expect the mould surface temperature to rise over 50 degrees celsius due to the exothermic reaction.
02:53	Reaching this temperature isn't uncommon on thicker layouts with more resin, particularly with epoxy which tends to have a higher peak exotherm.
03:01	Also the use of prepregs in an autoclave or curing oven will far overshoot this.
03:06	Chemical release agents tend to offer higher service temperatures.
03:11	A representative example is CR1 Easy Lease from Easy Composites.
03:16	This is suitable for wet lay, resin infusion and prepregs and is compatible with all standard tool surfaces, cure temps and resins except for polyurethanes.
03:26	CR1 comes in a liquid form and the recommended method for application is to apply to a lint -free solvent application wipe like you would acetone to a rag and then wipe a thin film over the surface.
03:39	As the film begins to evaporate, which should only take a few moments to about 30 seconds depending on the ambient conditions and the thickness of the film, another wipe is used to lightly buff the film even and remove excess.
03:52	For initial application it's recommended to apply six coats at 15 minute intervals and allow at least one hour afterwards before using the mould.
04:01	This is common for what's referred to as a semi -permanent or semi-perm chemical release agent.
04:06	Basically, it should provide good release for about five to ten pulls and as the performance starts to decrease a single coat can be applied to revive the release.
04:16	Another alternative is PVA release agent also called parting fill.
04:21	PVA stands for polyvinyl alcohol, not to be confused with polyvinyl acetate glue as they naturally function very differently.
04:30	The idea is unsurprisingly very much the same as other release agents we've discussed so far though.
04:36	It can be wiped or sprayed onto the mould surface and is compatible with polyester, vinylester and epoxy resins.
04:42	It's only applied in a single coat and left to dry for around 15 minutes or so before we can begin laminating.
04:49	PVA release agent is the best choice when there's a risk of poor release for any reason like part geometry or if we're using a polyester base mould with an epoxy part.
04:59	PVA will generally provide the best chance of a good release however it will leave swirl marks on the mould surface so it must be cleaned off and reapplied each time rather than our other semi -permanent options.
05:12	It will also often leave a slight texture on the surface of the release part that can be easily polished off.
05:18	A different form of release agent is release tape.
05:21	This is essentially tape with adhesive on one side to hold it in place but a release surface on the other side to prevent anything from sticking to it.
05:29	This is used for blanking off holes or other details on patterns or moulds.
05:34	For example when using the underside of a bonnet as a pattern, release tape can be used to blank any holes in the bracing and prevent resin from flowing into them.
05:44	It's also helpful for holding consumables in place during vacuum bagging or reinforcement in place during layup.
05:51	Release tape is also known as flash tape as it's used for taping around mould halves on split moulds to prevent flash.
05:59	Which is where the resin seeps into the gap and cures to form a small raised edge in the part that needs to be removed after with sanding.
06:07	These tapes often use a pressure sensitive adhesive so they don't leave any markings on the surface they're applied to and are also designed to handle high temperatures for pre-pre construction.
06:18	Again, there's many alternative products designed specifically for this purpose all with their own recommended application procedures and it should be mentioned that some other products that aren't designed specifically for this can be used.
06:32	An example of this is non-stick cooking spray or WD-40.
06:36	Depending on the product and the resin system we're using these might be compatible but it's important to do your own research here and use them at your own risks.
06:45	For those of you already familiar with the vacuum bagging process, peel ply and release film may have come to mind here as they're technically release agents.
06:54	These prevent other materials like the vacuum bag or infusion mesh from sticking to the part while curing.
07:00	However, as we won't be covering the practical skills of vacuum bagging or infusion in this course, we've covered these specific tools and consumables in the advanced composite course.
07:09	The key takeaways from this module are that release agents are required on the pattern or mold surfaces to prevent the mold from sticking to the pattern or parts from sticking in the mold during construction.
07:20	Chemical or wax release agents are applied to the mold surfaces as per the supplier's recommendations, generally building them up in layers for a semi-permanent release surface.
07:30	PVA release agents provide a more reliable release if we're ever worried about potential difficulties, however they're only single use so need to be reapplied every time and also require a bit more cleanup and post-processing.
07:43	Release or flash tape is another product used to provide a non-stick barrier, great for blanking holes and preventing resin flow or holding things in place during construction.