Mold making questions

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#1

I am just getting into the hobby of carbon fiber parts. I have ordered the following materials:

Carbon Fiber Fabric 2x2 Twill 50" 12k 19.7oz
Airtech AT200Y Tacky Tape Vacuum Bag S
Airtech Greenflow 75 Resin Flow Medium 41"
Spiral Wrap For Vacuum Infusion 1/2" OD 25 Ft
Carbon Fiber Fabric 2x2 Twill 50" 3k 6oz/203.43gsm Commercial Gr
Carbon Fiber Fabric Plain Weave 3k 5.7oz TAPE 2"
Soric SF 2mm Infusible Honeycomb Core 50" Wide
Airtech Stretchlon� 200 Vacuum Bagging Film 60"
Economy Peel Ply Heavy Duty 54"
Airtech - VAC RIC (Resin Infusion Connector) 1/2" Hole and Groov

I also have 12.5oz fiberglass and a vacuum pump. As far as I know I am only left with chemicals to purchase now. I am starting by making a front fender for a Cadillac CTS-V and have watched Easy Composites how to make a Carbon fiber hood as an example. After the tooling gelcoat, they use a skin coat on the fiberglass (I am having a tough time finding this in the U.S) I was wondering if this skin coat is needed or if I could just use resin like I was making a fiberglass part? Also I noticed the tooling gelcoat comes in different colors why is that? In the video I watched they used black and brushed it on, but everything I read on here says to spray it on?

I know there are a lot of questions here but I appreciate all the help I can get. Thanks!

#2

The skin layer is a good idea to do and is typically just a vinyl ester resin so you should be able to find this in USA. I guess everyday polyester resin should work too.

The gel coats are often black, green and reds. Maybe these colours are a harder resin (which makes better moulds?) but also moulds are often just a contrasting colour to the final product colour so spraying into the moulds easier.

Spraying the gel coat for making the moulds is best as brushing can show through due to the uneven thickness and shrinkage. If you know that brushing a particular gel coat is ok then just do this.

#3

The skin coat isn’t totally necessary. If you can get a vinyl ester laminating resin then that will be perfect (the skin coat is essentially just a high performance vinyl ester).

Tooling gelcoat comes in a whole range of colours, and it’s essentially just whatever the manufacturer decides to make it. There’s no real reason for it other than it gives you the ability to make your pattern a different colour to the tooling gelcoat you are applying so you can see if you are getting adequate coverage. EC like their black gelcoat because it shows scratches well so you can see how you are going if you need to wet sand it. Any low spots will be much easier to spot than on other colours.

And as for spraying vs brushing, that’s also sort of a preference thing. You can get a better application by spraying it (quicker too), but obviously you need the equipment, facilities and technique. Brushing can cause more errors but it doesn’t need any expensive equipment and you can do it where ever you like. Only thing to watch out for is that some manufacturers will produce a gelcoat specifically for spraying and so it will be thinner. This can then be very difficult to build an adequate coat and so can cause issues with improper cure etc. Just ask your supplier if their gelcoat can be brushed, if so then you will be fine.

#4

Thank you for the help. Can you guys recommend a resin for the carbon infusion that will dry absolutely clear? These parts will not be painted, therfore I am going for a clear gloss finish. I can clear coat them if needed.

#5

You don’t want to use Stretchlon for infusion.

#6

No stretchlon 200 for infusion.

What did your supplier recommend for a resin system?

You may also want to try a small simple flat part first so you don’t waste a lot of materials learning.

#7

I didn’t buy from a local supplier, it was online. If you just cover a body panel in carbon do you have to strip the paint?

#8

I ordered my material online not at a local store so nothing has been recommended to me.

#9

Where in Indiana are you?

#10

Mishawaka/ South Bend

#11

Any recomendations on where to get my tooling gelcoat from? I think that is the last thing I need to start this project. I think I would prefer to get the brush on kind not spray on.

#12

applied Vehicle Technology should carry what you need. And are GREAT to deal with

#13

IllStreet Composits has PE tooling gelcoat in orange and black in quarts, gallons and 5 gallon sizes. http://www.carbonfiberglass.com/Resin-Systems/gelcoat-gel-coat-polyester They are in South Carolina so shipping time should not be too bad.

It is meant to be sprayed, but I have successfully brushed it on small parts - 4 " x 16". I let is sit out in the mixing container for a few hours stirring about every half hour, before catalyzing so some of the styrene evaporates making it a little less viscous. It worked fine.

#14

I have made my mold but when separating the fender from the tool a small piece of gel coat peeled up in the middle of the part. Is the tool ruined now? Should I fill with more gel coat then wet sand or fill with some type of glazing body filler then sand? I need some guidance here, thanks.

#15

Nah simply fill with gelcoat and wet sand it down before compounding.

When filling with gelcoat, as it is air inhibited you will need to either use a wax-in-styrene additive or cover the repaired area with a piece of plastic to get it to cure hard. Then you won’t have any issues when it comes time to sanding it.

#16

Here is a photo of my tool. If anyone has any input on it I would appreciate it. I have put steel on the backside for reinforcement.

#17

It looks extremely thin. How many layers of glass did you use?

It also looks like there’s possibly quite a few voids under the gelcoat based on the condition of the flanges. This may mean you’ve got a bit of repair work on the horizon, and it’s possibly a good idea to hold the mould up to the sun to spot any voids and poke them out with a scalpel or chisel and repair them now before attempting to put the mould to use.

If there aren’t any voids though then that’s great and you can just proceed with repairing the damage that is present at the moment.