infusion...stopped! (hammertime?)

General Composites Discussions Showcase
#1

ok people i believe i’m one step from perfecting my process for infusion. Since i don’t have thin enough epoxy to infuse my projects, i’m just experimenting with polyester resin, but bear with me…

here’s how i do my stuff:

  1. Polyester mould with frekote release agent
  2. Clear polyester gelcoat applied, left to cure overnight
  3. aerofix spray adhesive sprayed , carbon cloth laid,
  4. i laid another layer of 100grm very thin woven fiberglass over that
  5. perforated release fabric
  6. resinflow mesh, applied to 3/4 of the mold… from the resin intake to 3/4 of the distance. (this is where things went wrong)
  7. bag it, suck it, and infuse it.

the pump i use comes from a big professional fridge so it’s very strong. The resin was moving fast, but when it reached the end of resinflow it stopped completely! i have used real thin epoxy with this kinda thing before but it kept going even after the resinflow mesh ended. i was hoping to slow down the process a bit this way so any air in the resin would flow away and the fabrics would be well wet… but instead i got the part perfect up to the resinflow, almost dry, and soft the rest of the way…

here’s the good side of the product, the rest i cut off and threw away…

it’s a car headlamp eyelid by the way, like this :

sorry for the big pics

i’ve already put clear gelcoat on my mold again, im trying again tomorrow!

by the way, frekote kicks ass! i’m saved!

#2

I like the photo of the car and shipping port, awesome look.

polyester resin will gel FAST especially if it is warm in the area/room. Use less MEKP, & perhaps thin down the resin a little bit with some styrene? Polyester resin is thick stuff.
What does your vacuum line look like where you attach it to the bag? Are you using any spiral wrap? perhaps use a small piece of spiral wrap for the vacuum line under the bag, like 5" long piece or so.

I hate it when sh*t goes wrong for me with composites work. So darn frustrating.

#3

well, this polyester resin is nice and thin… i used about 1,5% catalyst today (which is still too much i guess), and used resinflow mesh all the way from the resin intake to the suck point :rolleyes:

it has wetted out better, but there were still some dry points on the fiberglass (1st layer carbon, 2nd fiberglass)… i hope the carbon is well laminated, as for the glass, i can apply some resin with a brush on the back :smiley:

using the same resin, and only one layer of thicker carbon (around 350grm i guess) i had a perfect infusion… oh well… i’m not giving up.

#4

depending on your temperatures you might think about using only .5% (1/2%) MEKP.
It will take longer to cure but will allow full infusion.
Also I’ve found you should leave the part in the mold for atleast 24 hours with good heat on it to reduce fabric print through tip :wink:

#5

I know this is unrelated, but I’m thinking about trying a low cps vinylester resin for infusing. It will need to wait a while though, can’t stink the neighbors out here.

I would do that… use .5% MEKP. polyester resin gels very fast. Are you preheating the mold? If so I wouldn’t.

#6

with a vinylester infusion resin you will have about 30 minutes to infuse depending on the exact catalyst and %.the one I have used was 200cps and work very well

#7

vinylester indeed infuses very well, and the parts come out nice and flexible. The bad thing about making cosmetic carbon with polyester is you have to be careful trimming it because if you push it too far, it develops micro cracks around the edges. better to trim it not so “on the edge” and sand it down with a sanding block.

fabric print through is not an issue, i got a layer of clear poly gelcoat from 1 day before laid in the mold… i spray the adhesive on that, and lay the fabrics :slight_smile:

#8

As far as i have seen online at various suppliers vinylester costs only about $10 more for a gallon compared to polyester resin.

I’ve heard bad things about polyester resin and gel coat cracking. Those are just my viewpoints so if you are happy with polyester use what you feel works best for you.

#9

Gel coat cracks when it is put on too thick. and when infusing with polyester or vinylester you get a high fiber content than standard open molding techniques. Polyester/vinylester parts have a bad rep because of open molding techniques that have very high R/C. you can make a nice part out of mold from infusing with vinylester without any clear gelcoat, and will not be noticably weaker compared to epoxy.

#10

i don’t have a problem with epoxy, i just don’t have one that is thin enough to infuse. I’ve infused with all 3 resins, vinylester is very good, only bad things are the colour, and the stench …

anyway, last night’s infusion was the same, using resinflow all the distance… The catalyst was too much i guess and the resin gelled too early, resulting in a “dry area” near the end of the product. hey, it IS an improvement…

the dry area:

today, i used a lot less catalyst (around 0.5-0.7%) and i also used spiral wrap on the vacuum side, to have a greater area of vacuum. as the infusion was ending though, i got a hole near the intake and filled the thing with bubbles :eek: i hope the item is saved…

#11

That part should infuse in about 30 seconds.
If the resin is gelling before it’s done infusing, you are adding WAY too much catalyst.

#12

so i guess my resin is too thick then…

#13

1: Love the car pic. Great backdrop, maybe change the white balance a bit, to get some more orange out (not all), and start selling the photos!!!
2: yeah, it should infuse fast. If not, resin is too thick, if so, less catalyst! I have reinfused bad infusions in the past with success. But that part seems to have wrinkles in the end, not just dry spots. ?

#14

its not wrinkles, its the gelcoat which has taken the surface of the fibers… anyway with a few layers of clearcoat it may be saved.

WEIRD THING HAPPENED: the infusion that popped a big hole and was filled with bubbles depressed me, so i didnt work on the shop for 3 days, and i stopped by today to take something, and i said, why dont i demold it and see what happened…

…it was perfect. the first perfect infusion i have ever had, and it happened on a part i thought i would toss to the garbage for sure!

well, that lifted my spirits… photos soon.

#15

You had a bag blow while infusing, and the part turned out well??? wow. Hope all the bubbles aren’t inbetween the layers!

#16

fact is, i had one layer of 240 or 290 grm carbon, and one layer of around 200 grm fiberglass on the back. those two were not bonded well together, but i applied epoxy with a brush and it was fine. after all, its just a cosmetic piece, a headlight eyebrow, it doesnt need real strength. what i was looking for is goood looks.

tomorrow im getting some real infusion epoxy, so, we’ll see how it goes :rolleyes: