Motorsport Composite Fundamentals: Wet Layup - Hand Lamination

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Wet Layup - Hand Lamination

06.05

00:00	We've now reached lamination, which could be considered the main step of composite construction.
00:05	We'll be doing this in a single stage with a waxed laminating resin, as opposed to the multiple stage approach we use when making these moulds, with a thin skin backing layers and an unwaxed resin.
00:16	As such, it's important that we keep the pot life and working time of the resin in mind throughout the process, being sure not to run out of time while we're still working.
00:26	This means we need to be sure to have our resin on hand in appropriate amounts poured into mixing containers before catalyzing.
00:33	It's also best to work on a single mould at a time if we're working alone.
00:37	As we discussed in the preparation module, we'll be using a resin filler aka resin bog to help prevent voids in our part around some tricky to laminate areas.
00:47	So, let's start with that.
00:48	The first step is pouring out a known quantity of polyester laminating resin into a mixing container.
00:54	It's important to remember this quantity as it's what our catalyst volume is based on, not the thickened mixture.
01:00	We've used about 400 milliliters of resin in this case, but honestly we could have gotten away with about 100 milliliters as we didn't end up needing to use much of the resin bog to fill the irregularities in the mould.
01:13	Before we catalyze we'll gradually add cabosyl to the resin while thoroughly mixing.
01:18	The aim here is to create a smooth paste about the consistency of peanut butter that we'll be able to paint onto our mould in detailed areas and it'll cling in place nicely.
01:28	Again, keeping in mind that we'll be wanting to laminate within 30 minutes or so from when this resin bog is catalyzed.
01:34	We'll set this aside for now and pour 200 milliliters of resin into two separate containers that we can catalyze separately.
01:41	We prepared two 400 milliliter containers for our mould which was a much thicker laminate and had plenty left over, so two 200 milliliter containers should be a good starting point.
01:52	We've also got some 225 and 450 gsm chop strand mat and 200 gsm plain weave aka 6 ounce boat cloth cut and prepared from earlier.
02:03	With everything laid out and ready to go we can now catalyze the resin bog at 2% of the original resin volume, so 8 milliliters for 400 milliliters of resin, mixing thoroughly.
02:13	We'll be able to see a color change occur, in this case from blue to green after a while of mixing.
02:20	Then we can use one of the smaller brushes to start applying the bog into the tight details and over the sharp edges, essentially anywhere that could be difficult to laminate.
02:29	We just want enough to help fill out the very tight areas and small irregularities, but not so much that we'll end up with large pockets in our laminate.
02:38	With the filler in place we'll catalyze one of our containers of laminating resin and mix through.
02:43	I don't want to sound repetitive here but it's critical to ensure we mix fully, always scraping down the sides.
02:49	Any areas that don't cure could potentially ruin the part.
02:53	When we're happy we'll start by laying down a coat of resin over the back of the gel coat, then it's just a matter of laying up our reinforcement with the cut edges into the corners of the part to get the reinforcement as close to the surface as possible.
03:06	Torn edges are good for overlaps to create a more seamless transition.
03:10	As we lay down each layer we wet it out fully by brushing and dabbing with the brush and then rolling it out to consolidate the reinforcement before backing it up with the next layer.
03:20	When rolling we're usually able to hear an audible difference as there's no longer bubbles in the laminate and we'll also be able to see the air bubbles leaving the back surface as we roll to ensure that we've fully got them all out.
03:32	Remember the plan here was to use two layers of woven reinforcement on the mounting flanges and back this up with a single layer of 225 mat.
03:41	The rest of the part will have two layers of 225 gsm mat backed with three layers of 450 gsm mat.
03:47	As we covered in the mold making section of the course, sometimes the mat will be difficult to conform around edges and to details and if we wet the mat out and leave it for a few minutes to dissolve the binder, the mat will be more pliable and help with this issue.
04:02	If we don't have a suitable dibber, a thin popsicle stick can help to push the reinforcement into tricky areas like under the mounting tab for the door jamb.
04:11	With the reinforcement fully wet out we can roll or squeegee out the excess resin onto the flanges that will be trimmed off the part.
04:19	It's important that the reinforcement is fully wet out to avoid dry areas that will delaminate.
04:24	However, excess resin won't only be heavier but it could also cause hot spots while curing that would lead to local shrinkage in this area, basically a weak spot in the laminate that could ruin the whole thing.
04:36	One last consoleration and dab into the sharp details to help prevent voids and we're done.
04:42	Making sure we've disposed of the leftover exothermic resin safely by dispersing it into smaller and thinner mixtures and allowing it to fully cure in a safe environment away from anything flammable or combustible.
04:54	The cure time is about seven hours but again leaving it as long as possible, even a few days is ideal.
05:01	In this case we laminated the fenders in the afternoon and came back to demould them the following morning.
05:07	During this time of the year the nights were getting a bit colder in Queenstown so we left the heat pump running to keep the room at over 20 degrees celsius to help ensure the parts would cure overnight.
05:18	We'll come back to cover the demoulding process as well as any finishing touches for our fiberglass fenders in the following modules so for now let's just recap our lamination stage.
05:28	To prevent voids and difficult to laminate areas we primed the mould with a resin bog or filler which is essentially resin thickened with fumed silica or cabosil.
05:38	After this we laid down a coat of laminating resin to wet the back of the gel coat before laminating with boat cloth on the mounting flanges and CSM over the entire part.
05:49	It's a relatively straightforward process of wetting out and consolidating while keeping in mind the limited working time and avoiding areas of excess resin.
05:57	After finishing we need to allow the layout to cure and dispose of our resin safely.