Problems infusing with Fibre Glast VER?????

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#1

I also posted this on the FG BB, but wanted to check here also.

Has anyone had problems infusing with Fibre Glast vinyl ester resin? More specifically, I have made a couple hoods not where there has been incomplete wet-out of the carbon fiber between the clear gel coat and the fiber surface causing a slight bubble effect. This would be the surface that is face down in the mold. When I remove the flow media and peel ply, the surface of the piece looks completely wetted out, but once I remove it from the mold, I see these foggy patches. As a side note, the clear gel coat is also the Fibre Glast product. I have tried infusing a couple hours after spraying down the gel coat and also waiting for complete cure first, but experienced the same problem. Here is a pic of the issue -

You can see on the driver’s side and in the middle some foggy patches where the resin did not completely wet out.

Now, here is my take on this and tell me what you think. I have had successful repeated infusions with different epoxies, but almost always had some type of issue with VER. One thing that I forgot to mention was that I typically cover the entire surface with a flow media (red netting stuff) and double up on edges and create some flow channels down the middle of the hood. I was thinking that the resin front was advancing too quickly with the VER due to the lower viscosity. With the epoxies, the resin front moved more slowly and maybe this lends itself better to a complete wet out. Thoughts? I was thinking about trying another hood that I did not cover completely in flow media but only created feed channels. This way the resin front would be slowed down. However, not being crazy about wasting the money on another hood, I thought I would run it buy the collective wisdom. Another piece of info is that I am infusing using a Ritchie Yellow Jacket vacuum pump at about 29.5" hg vacuum.

Here is a pic of the infusion. You can actually see a two front infusion. There is the surface layer which wets out more quickly then there is the layer below and including the peel ply which wets out slightly slower.

Here is a pic of the hood just before infusion to give you an idea of the flow media layout.

#2

The 2nd infusion pic shows a “bare” spot where the resin has entirely encircled a spot that corresponds to one of the hazy spots on the hood.

So here’s my wild ass guess…

Even though the part is under full vacuum, there are still some air molecules dispersed through out the laminate. When the resin encircles an area, it corrals that air and it stays entrapped and contributes to the hazy areas.

See the green circled areas…

I would rearrange the way the part is infused, so the resin flows in a linear fashion (or close enough) so the resin can’t create these pockets and encircle an area in the laminate before it fills.

Just my opinon & everybody’s got one - Bob

#3

Hey Bob,

Thanks for the idea, you may have something there. As a next step, I was going to try a couple things.

    • Reduce the number of layers from 10 to 8. This might lead to a more complete wet out.
    • Save some money by using glass instead of carbon for these trial hoods until I can get this problem nicked.
    • Only using flow media to create flow channels and not cover the entire hood. The thinking was that this would slow the resin front and get a more complete wet out.
    • Since I did get some print through from the feed lines, move the feed lines to the flange furtherest from the vacuum port. This should then create a single resin front as it flows across the piece.
    • Shut off the vacuum sooner after complete wet out. I have typically been leaving the vacuum on for 30 to 45 minutes allowing for the resin to gel. My thinking was that I did not want to have problems with rebound once the vacuum was lifted. However, maybe the additional vacuum time is contributing to the dry spots by pulling out resin. Don’t know for sure, but I will give it a shot.
    • Make a good hood first using epoxy just to make me happy! :smiley:

I will post my results. Thanks again.

#4

Kevin,

Try placing the feed points/lines differently. From the way it looks you are getting resin starting at multiple location coming together creating a trap. This is fine if you have your vacuum point right in the middle of that.

#5

How about tipping the mold so the resin flows from the high side down to the vacuum (low) side in more of a single wave?

#6

as a person who doesn’t use this method, but just an idea… what about rollers?

#7

OK, here are some more pics of the actual hood that came out of the mold so that you can clearly see what I am talking about.

Here is a picture of the hood straight on -

Here are some of the problems with incomplete wet out -

For reference, here is a pic of what print through of the feed lines looks like -

#8

Jeremy, you don’t use any rollers or brushes with this process, check out Evan’s tutorials for step by step demo.

JM

#9

Jeremy, you don’t use any rollers or brushes with this process, check out Evan’s tutorials for step by step demo.

JM[/quote]

is that to say that you shouldn’t ever use rollers because it could cause more problems than it solves, or that if the feedlines are correctly placed you’ll never need to.

It seems like if in a pinch, the rollers would help eliminate as much of the dry spots as possible

#10

I’ve seen another shop use a rubber squeeze to help push the resin around and get a better wet out. I’m affraid to use rollers in case it punctures the bag. Having any leaks during the process would basically ruin the part. The problem here is you can’t see where the dry spots are going to be. Kevin this is off the wall here but are you using tack spray to lay down the cloth? I’ve had problems with tack spray vs. vinyl ester also when I used to infuse with VER

#11

Yes, I was using Super 77 as a tack spray. I can try without.

#12

Kevin, I only use vinyl ester resin. I can see one huge problem with what is happening her. You either need to infuse from the center going out, or from one side to the other. you need to infues your part so that no areas stand a chance of isolating an area of its vacuum. it is like painting yourself into a corner.
I use vinyl ester everyday…(am I on fiberglasts forum…OK, I can speak freely…(grin).
I have not used Fiberglasts vinyl ester resin. Mine is mixed specially for my application. I also do not use MEKP for infusion. I use a special blend of Norox, formulated to have a low exotherm. this also does not produce the bubbles that MEKP would produce. I don’t have to vacuum degass my resin once it is mixed.
I always pull from one side to the other. I lso do not place my lines on the surface. I place them up into a crease in the bag, so I don’t have a chance of producing any exotherm on the face of the part. the amount of resin in the tubes will exotherm enough to leave marks that deface or look odd on the surface.
I place my resin lines no more than 10 - 12 inches apart to allow for quick entry of fresh resin all along the route.

#13

Ougie, isn’t Norox just a summer MEKP? I got a jug donated and was told that and just waiting till the heat of the summer gets here to try it.

#14

That may be true, But this is formulated for slower exotherm and low foaming.
I will ask about that statement.