Yes and yes (vacuum bag)
I would say that you are having a reaction of some sort with the release. The mold has clearly lost it’s gloss after the first part is pulled. Did the part release difficultly? Did you fully buff the release wax to a shine? Does the mold surface gloss up with a fresh coat of release wax? Is the mold surface now permanently dulled? What kind of resin? Some resins do not play nice with some synthetic based releases like yours.
Yes it was hard to release as you can see part of the mold was damaged. I did fully buff to a shine… 4 coats and it glossed right back up. I don’t think it is permanently dulled. I will need to look. I was using a system 3 on the 1st 3 layers and a cj composite epoxy on the remaining layers.
http://www.systemthree.com/store/pc/Clear-Coat-c14.htm
http://cjcompositestechnology.com/epoxy-resins/epoxy-resin-system-for-carbon-kevlar-15-gal
I have uploaded a high resolution pic that you can zoom into more clearly. Also attached is a panel I made using the cj resin, mylar tape and no mold release.
Any thoughts on how to save this part? make it glossy?
The part can be clear-coated to make it glossy.
I would say that the dull finish was a release issue. What was the surface coat of the mold made from?
It is Feather Fill. I don’t have a spray gun so i am not sure if i can apply a pva without issues.
Pva or go with a semi perm release. Wax alone is a bad idea. I would rather brush pva and deal with the wet sanding than trust just wax.
It would be nice if the pva came in a spraycan. Does the hair spray thing work?
The part you see is for the wing bottom. I still need to do the top which I want to make nice.
I pick pinholes clean with an exacto knife and fill with the same resin used. Then carefully sand flush.
Just my opinion, but as you know epoxy has terrible uv protection. I already knew I needed to do a 2k clear of all my parts for proper uv protection. My parts so far have looked worse than yours. After pulling I hit it with 800 grit, clean part with preferred degreaser (alchohal for me), paint with Shopline PPG 2 part clear. My parts are small so even my $180 26gallon HF air compressor does the job. I use a $20 hvlp harbor freight gun with the supplied 1.4 tip. The clear I got was like $80 maybe and will cover a ridiculous amount of parts. And it’s a good skill to have. Added benefit is you can also spray Pva, which I haven’t tried yet.
ok I ran the top part. this time i tried to spray on a pva but it fished eyed real bad. So i cleaned that off and just wiped it on. (pic attached)
The part popped of like nothing and the mold stayed undamaged!
I also didn’t use the super slow curing resin like i did the first time. Maybe that is the reason for the added pinholes?? The pic with the two wing halfs shows the old one (background) and the new one.
Thoughts?
Can I just spray a 2k clear over it with out filling in all of the pin holes still have it come out nice??
Oh boy! That’s some pretty serious surface issues I would say. I would if that we’re my part sand it down with at least 180 grit and bring up to 600 before clear coating to get rid of all the holes. I think with a bit more practice with that layup you will achieve much better results.
Would you please share the fabrication process of the wing?
Yeah but i only need one and maybe one back up ;/
If i sand down to 180 it will remove all of the top layer resin though. Wont i need to apply more resin after that then sand again?
How the two wing halfs will go together? Layup? Mold mfg?
Try sanding down the test panel with 180 and then 220,320,wet320,600,wet600. Then clear coat and see if you like it. You should be able to rid it of those holes without too much filling or noticeable defects. Use a soft foam block as well. Shouldn’t take too long.
I’ve actually found the easiest way to fill holes is to use a regular body filler and colour it with a black pigment. Easy to apply, sands down super easy, and is virtually invisible when you apply a clear over the top. So far I haven’t had an issue using regular polyester filler, but if you’re worried about it you could always achieve the same thing with your epoxy and some microballoons.
Obviously filling with clear coat or resin is better if you have the patience, I just don’t have the time for it.
I do to same thing if the holes are big enough too. And yes! I’d love to see how you put this wing together.
Any examples of that filling technique? How does it not show as it wont be painted afterwards. I have a lot of holes to fill to salvage this top half.
So I made the two mold halfs which i cut out using a 3d router and a bunch of MDF glued up together. Next I laid up the carbon fiber which was 3 layers of 3k, 2 layers of fiberglass (rock, chip protection), 2 layers of uni, 1 layer of 3k.
I left a 1.5" flange all the way around so that i could put a small strip of carbon tape between them before clamping them back between the two mold halfs for joining. This will eliminate any gaps between the two parts after trimming. Shown green in the attached pic
Also while the two parts are clamped together, i plan to run a .500 carbon sock down the length of the part and inflate during to cure to add even more strength like a spar. Shown in blue.
However if i had a bigger oven i would have done it like this…
http://www.compositesworld.com/articles/high-speed-press-cure-for-high-speed-racers
Any thing else you are curious about?
Very cool. Answered all my questions!
Bondo with black pigment is a fast fix like hanaldo said. It does catch your eye tho. I’m a bit OCD with stuff like that so most times I block sand and then clear coat. For big voids i will fill with resin pigment and silica.
Bondo and pigment is easier and faster.
West marine carries pigments in white blue yellow red and black.