Im a noob to composites and wondering if the special gelcoat cup gun I see advertised is a good investment as I plan to make many parts?
in your opionion, it makes sense IMC if the mold isn’t high gloss? With resin infusion and also RTML I have little pinholes in the piece…it makes sense to do a IMC, then infusion/rtml and then an other finishing coat?
2K paint is lighter than gel coat, and his cure cycle is shorter
I use IMC since 1 year with infusion. For me it’s a good solution when you can’t apply a top coat in good conditions.
I apply my IMC with a spray gun, if your mould has a good finish surface, your final part will have a beautifull surface.
If you have some dust when you apply your IMC or during the cure, those imperfections doesn’t really appear after infusion.
On the specifications of my IMC, you can wait 72h before infuse. Generally I put my IMC at the end of the day and infuse the next day. I prefer to wait because if you put to much IMC, you can some issues because the IMC doesn’t catalyse correctly.
In my opinion IMC’s do not make sense if:
- The mold cannot produce a high gloss orange-peel-free surface. The IMC can be polished if it’s slightly hazy. Semi-permanent releases will sometimes get hazy after many molding cycles. This haze can be easily removed on the part by using a Swirl Remover and few minutes of hand work.
- The layup contains voids. Voids cosmetically will not look good even if the IMC is spanning them. The IMC is also prone to breaking if it’s spanning a void.
- The resin and curing technique do not eliminate fabric print-thru.
i tried an IMC for the first time a couple of days ago… i used a 2pk epoxy high build primer paint and built up a reasonable thickness, waited 4hours then laminated over with epoxy matrix e-glass multi-axials. So far everything looks fine and no noticeable pirnt, however it has not been exposed to sunlight yet and i suspect it might show up then… i also have some 2pk Extreme hard wearing epoxy finish coat to try (used on oil rig pylons), i cant see it being much different as i beleive the chemistries are similar so it should work ok and provide a super tough exterior coating… i think the trick would be to simply infuse over this type of coating within the “recoat window” of the paint so its still chemically active.
Thanks for the tip…
ok thanks wyowindworks. This morning I have do an infusion in a half IMC mold, this afternoon I demold and then I will see how it is. I have fabric print-thru also with a test with rtml, 1 layer 200 gr carbon + 1 650 carbon, with much resin, but there is always a little print-thru.
I post a picture this afternoon
- If the part is too big to be filled with dry material and infused within the open window.
For the rest, nothing but good things about it.
I have demold 3 hours ago. I have a lot of print-thru, but I was a vandal with the cure…infusion at about 30°C, then oven @ 50°C for 20 mintues, then without ramp 70°C for 25 minutes and then 10 min @ 80°C, 5 min. to cool down until 60°C and demold
A question about print-thru and class A finish surface… Class A surface is 100% print-thru free? Yesterday I see Gurit sprint prepreg and a test piece make with this…it’s class A surface finish, used by Aston Martin to make hood, fender and rear hood. It has some print-thru
Then it is not Class A, but marketing BS.
Class A is like a mirror, and a very good one.
Even the tempered glass sheet we use for testing already has some waviness. Enough not to call it class A.
Do the ruler test. Position a ruler on the part, and see up to how many cm or inch you can read the markings on the ruler. The more, the better.
If I understand right, class A surface in automotive isn’t a mirror surface, but a surface ready to paint.
This is the prepreg
http://www.gurit.com/files/documents/automotive-brochure-2011pdf.pdf
with a single layer of this prepreg they made the outer side of the bonnet, front wheel arches and rear tailgate.
just a quick question… I’m about to embark on my first mold of a Harley fender that I customized…
I love the idea of spraying the clear coat right onto the mold surface but whats a brand of High slip mold release? Do you mean just using something like partall wax? I have to assume that PVA will not be that friendly to PPG/Deltron clears…
I use Frekote 770-nc. You can also use Dolphin wax which is easier to spray on top off. You just need to test that the whole system will release (release surface + release + IMC + layup resin). Test everything before committing to using your chosen system on the actual mold.
Anyone ever have issues with cutting afterwards? I know that sometimes when I’ve cut things in the past with clear coat on it’s either chipped or lifted drilling a hole or cutting.
Any tips? I had something recent happen when I was trimming along the edges of a piece my cutting wheel I think was dull I was using so it would heat and smoke the material slightly. I’m guessing it heated the cleat coat and made it lift in small areas.
BTW the piece was just a test one for fun.
Oh, and this was on a mould that I used 3x layers of dolphin wax
Layup schedule was 5x of carbon
2x 6k twill
1x 24k standard
2x 6k twill
Infusion time took about 20min with a 1/4 inlet using mti hose. After about 8 hours of rt cure I post cured at 140. Resin is Rhino xxxx whatever infusion resin medium hardener.
Do you have a picture of the piece? Id like to see how it came out with the clear coat.
I know everyone here is enthusiast of in-mould clear coating but In my opinion it has few disadvantages , first of all you need trim edge and you can break the clear by heat coming from dremmel, also by cutting off edge you make yourself a little harm, because If you dont have clear on edges it may go off like sticker, and the last thing… If you get an air bubble between layup and clear you are f****
Also if you apply clear coat in the mold prior to layup dont you have to finish the edge of the parts after you trim them?
Send me a PM with your email and I’ll shoot you a picture over. I actually gave the item away because it was a present anyways, haha.
It really depends on what you produce. Almost 90% of what I produced was hollow molded structural components. It made a heap of sense for me. I saved 10 hours of labor per week by using an IMC. I also did open structures using template cut patterns so no trimming was necessary after demold. All that trimming and hacking can be very timely.
I agree and would love being able to bypass the need for final cutting and finish. Can it be done without expensive cutters and pre preg?