I am guessing that you have tried the part again…There are a couple of other things you can do if not.
Firstly, don’t use the gel coat, as it’s not helping.
I nearly always do wet layup using plastic as a backer.
I will explain-
Get some cheap thin plastic 50-75um (micron) which in real terms is about as thick as the vac bag you are using, but much cheaper.
You can use 3M masking film, or even shopping bags but it’s a little harder!
The plastic is stretched lightly over a flat table and taped out so there are no creases. Ensure there is enough area for all the layers.
Lay the fabric out on the plastic.
At this point I become very fussy about ensuring the weave of the RC200 is not wavy or distorted, and tease out any imperfections.
Wet out the fibre with your chosen resin… I use plastic squeegees to do this as once the fibre is wet out you can apply additional pressure to remove the excess and even out the resin content. Rollers work, but can airate and mar a cosmetic carbon layer.
Pool some resin in the centre of your fibre. Using the squeegee divide the pool of resin and sweep it out with one direction of the fibres… Ie @0 or 90 degrees.
Go back to the remainder of the pool and sweep it out the opposite way to the first sweep.
Apply some more resin and this time do the same but at right angles to the first.
You have made a cross of resin that has secured the warp and weft of the fabric.
Carefully wet out the rest of the cloth with the residual on the plastic and by adding as necessary.
When you are content with your wet out, it is even and not excessive, untape a corner or two.
Carefully lift up the plastic to view the underside… You should clearly see the fabric is wet and contains no dry patches etc… If it does remedy them now.
Cut the plastic around the fabric.
The plastic is then a transport film like prepreg backer.
(Note: If I am making parts with complex shapes or a large number of plies, I will template the plies and nest the shapes onto a second plastic layer. Lay this ontop of my wet out fabric… Then cut out through both layers and the carbon at the same time.)
Back to it…Apply a thin layer of resin into the mould
Then bring the wet out fibre to the mould and lay it down plastic side up.
Being as your first ply is at 0/90 I would start working the fibre into the mould up and down the centreline then moving out wards.
Once the rigidity of the plastic is working against you, begin to remove it. It will peel up away from the laminate quite easily.
Use A small dry brush to help tease the fibre off if you need too. Avoid lifting the fibre out from the mould or distorting the fibres as you peel.
Using a dry brush, gently stipple and work the first layer into your mould. No need to add resin as you should have plenty already.
When you happy the first layer is down and not bridging in the corners, bring over the second layer and repeat. Then the third and so on.
No need to be as anal about distortions with the subsequent layers, just be mindful that you may be moving the first ply underneath with the upper layers and that will be visible in the end result.
Now: Vac stack…
If any part I am laminating has complex or compound curves, I will cut the peel ply on the 45 degree bias.
Really seems to help with both bridging and wrinkles.
Rule of thumb- All internal radius’ should have a slip joint. I.e: The peel ply is cut and then a second piece with an overlap is added.
This apples to the perf film too, so I like to pre apply the peel ply and the perf together with spray glue (3m 77) and then you cut down on the time it takes to lay your vac stack by laying both at the same time…
The breather should be able to stretch and allow for small contour variations… But if in any doubt, cut it and add a slip join…
Pop your part in the bag and pull the bag down with the pump moving the bag into the internal radius’ until it is just about to start ‘pulling’. You want most of the air evacuated, but still be able to move the bag easily.
Rule of thumb- you need a fold or pleat in all the internal radius’ and try to eliminate any folds on external corners. This will help the bag pull into the corners and stop unsightly wrinkles on external.
Then apply more vac, turn off and check the bag… Repeat until you are at your desired vacuum.
For a better assessment, it would be useful to show a few pics of the part in its bag.
The Perf you are using - P3, is okay for wet layup… But only just.
Perforated films are graded in two ways - ‘Open area’ and ‘hole density’
Hole density is the spacing of the perforations
Open area is driven partially by the density, and by the perforation size and is the total area of all the holes added up in 1m2 giving you a better idea of how easily resin will flow through.
My preferred is by Airtech and is P31 which has a hole spacing of 25mm which is less density and open area than P3
As P3 is less than ideal, you need to be careful applying too much vacuum, or in this case I feel your applying it much too soon.
Lookup the gel time for the resin you are using. For cosmetic parts, you want to be applying vacuum very near the time the resin begins to gel.
This will give the resin less flow time - and will keep the resin where you want it.
Forgive the marathon post, and I hope it makes sense. If I had some pictures, I would have posted them as it would have saved me writing it all…
You can try this method on scraps to see how you go.
Good luck!
