greetings everybody… following my last thread (VIP schedule) I tried to infuse a sandwiched laminate and these are the results… 
I perforated the core approx 25mm centers / 1mm diameter and made shallow grooves on the bottom side. 1 layer carbon, core (divinycell 1/8"), carbon, peel ply, flow media and bag… as you can see in the picture the resin did not even covered the top side and the bottom was even worse… i also used silmar 249 polyester resin … (it was a hot day though)
what went wrong and how can I fix it?
I do think that I should have placed the resin feed line and vacuum line the other way ( along the longer side) and maybe use spiral tube instead of the vacuum connector…
I appreciate your feedback.
end the flow media shorter than the part will help a lot. also a slower flow would be more desirable.
Yuck.
Your using no peel ply?
You killed the infusion by not segregation source vacuum from the resin flow media. Your infusion stopped as soon as your flow media saturated.
Basically where your vacuum port sits all that material needs to be covered inside the bag with a barier layer of film so that all the resin in the flow media can only get to vacuum is through the perforated film. In your case resin traveled through the flow media and then right to the vacuum port and bam. Infusion stopped. Then your carbon just wicked resin which is why you have the fade in your laminate.
Ok. There’s a few things here.
- Gel time of the resin. Looks like it gelled on you.
2.Not that it looks like it’s happend but you can ramp your core on all edges to help stop race tracking. After a few trials you will probably get away with out it but to start with its worth doing as it helps take away another variable. - Stop your flow media about an inch away from the edges of your panel except the edge that you’re feeding from.
- Is that resin “infusion resin”? If not, you are honestly wasting your time. Standard PE and VE resins will boil styrene under vacuum and viscosity is too high. Epoxy however is possible to do smallish jobs with standard laminating resin it just depends on gell time.
- Pe resin and carbon? Using pe resin with core and carbon, the resin is the major weak link in this equation. Carbon is a high performance fibre to get the best out of it you need to use a high performance resin ie good quality epoxy (not epoxy formulated for laminating over timber).
- As mentioned that flow media is crazy quick. Everyone’s different, but I prefer to use a slower flow media than the green.
Edit. I just googled silmar 249. Sorry, wrong resin. Surfboard laminating resin is has a really short gell time.
If you want to make this laminate in one shot you have to use a special vacuum infusion epoxi and high vacuum.
You need the high vacuum to close the small dry spots you produce with resin. Using a Polyesther resin will not work because the high vacuum will cook the resind so that gas will fill the dry spot and not resin.
The other thing i agree with brad.
Yes and as DDC said, High vacuum. How much vacuum did you have?
Thank you brad1 for your explanation. it did seem that the resin started to gel and it was a very hot day…
Next I will cut the flow media shorter as you mentioned, however, what kind of epoxy resin would you recommend for vip?
and vacuum was at 27.5 In Hg.
Has one of you ever tried to cook polyester resin? I tried with a bucket of styrene, and water boils quicker. Although you can boil off styrene, water content of your materials is a bigger concern. (keep a good vacuum on (20 mbar abs) for at least half an hour to boil the water off).
Indeed Silmar 249 is hand laminating resin. This means the rheology is completely wrong for infusion:
When worked, the viscosity drops from some 2000 cps (or even more) to a low 500 or so. (or even less) so it is easy to laminate. When not worked, viscosity rises to this 2000 cps or more again. So when the resin slows, viscosity rises, slowing the resin even more, etc.
There is a bunch of rheology modifiers in the resin to do this.
Infusion resin (polyester, epoxy) do not have these modifiers.
my 2cents.
1: distro media 1-2" away from end of part, followed by a layer of peelply to the vacuum line. The sides, I’d trim to 1/2" from end of part.
2: 1 layer /core/ 1 layer is hell to infuse anyway.
3: your vacuum port doesn’t look like it is touching the part in any way. Again, layer of peel ply a few inches away frmo the part, TOUCHING the part and the vacuum port. This way you will always have flow to the vacuum port.
4: if that is pretty quick flow media, and since a single layer of carbon will infuse slowly, slow down your resin input flow!! Maybe slight clamp the resin line, or do it in pulses while watching it. This way, your bottom layer will have time to catch up to the top layer and distro media.
5: to save your vacuum line, do the same thing you did on the resin inlet. Just stick a tube in the bag seal, or some spiral wrapped in peelply. Then you can just toss it if it gets filled with resin.
thank you all for your help… what (clear) epoxy and polyester infusion resin do you guys recommend?
I have no idea of what is available in your area. Consult some suppliers, and specify it is for infusion.
Huntsman Araldite MY721
snicker
nono, I kid. I wouldn’t recommend the most pain in the arse infusion epoxy to a newbie. cPs is 3000-6000 at RT, and 1000 at 120f.
Can i just ask why this is good practice 
In vacuum infusion there’s two planes of flow. One is above the fibers(parallel to fibers) and one is vertically (perpendicular to the fibers)
Flow media allows the resin to flow above the part. If it’s too long the resin will “racetrack” over the top of the fibers and get sucked into the vacuum. By cutting it short the resin will move quickly through the media then slow down dramatically at the end. This allows enough time for the resin to flow downwards into the fibers.
helps reduce swelling at the resin inlet side of the laminate, reduction in void content.
I’ve seen a 12"W x 30"L stack of fibers where only the first INCH on the bottom was wetted out. You can pull all the layers off one by one, and see the progression of resin to the 30" mark on top. Some fabrics just hate resin!
Ahhh this could be the anser to my problem. thanks fo the information.
Canyon said exactly what I meant in the beginning. Sometimes my post go to far into depth and loose the simple explanation I started out with. Sorta like … ah f it!
I checked with fiberglast.com fiberglasssuply.com and uscomposites.com and none of them carry any clear infusion resin… any other suppliers you guys know that I can contact? (i live in so cal)