Infusion Q&A

We build kayaks and surf skis by infusion,4 "shots' every week, you can either core infuse with grooved PVC foam or SORIC,which makes for stiff but heavier boats ,or use a mesh as a flow media and therefore a lighter core. we use FGIs VE resin because it cures faster and is compatible with our polyester Gelcoat compared to epoxy.

 

The below link should help a little.

http://www.thag-o-mizer.net/infusion_page1.html

alan

 

Andrew:

Would you share the brand names of the resins you are considering?

As you go lower in mPas does the price go up?

alan

 

Alan
In general to maintain mechanical properties as you reduce viscosity means having to use more expensive components. For this reason infusion grade epoxy resins are more expensive.
As a starting point when selecting a resin first determine what mechanical properties you require and what temperature you are capable of curing at. Then get the data sheets from the suppliers to see which resin systems will meet your requirements and at what cost.
I am considering products from two local formulators.
http://www.atlcomposites.com.au/atl_composites/
http://www.vee-tek.com/Products-by-Industry/Marine.aspx

 

Thank you Andrew.

I have spent many hours researching epoxies and have not run across either of these.

Alan

 

For epoxy, this is completely true.

Polyesters are easier, as these come in a very liquid form, and need to be thickened to become hand laminating polyester. (price difference is negligable)

 

Alan, As I said ATL and Vee-Tek are local formulators, that is why I suggested SP and Sicomin as they should be available to you. Having said that I think VeeTek have some form of association with MID American Supply Corp or MID American Composites that you may want to follow up.

I will need to make my choice soon, I like the ultra low viscosity 150mPas at 20'C and the very high 14% elongation of the vee-tek product but it does require post curing.
While ATL have a ambient temp cure hardener for their R118 resin, viscosity of 200mPas at 25'C but the tensile elongation is below 5% that I was looking for.
I dont know how much of a benefit the much higher elongation is to me, ideally you would have specimen laminates of both tested but this is too expensive.

Andrew

 

Just got an e-mail back form vee-tek.

They hope to manufacture in the U.S. sometime in the next 24 months.

Since I'm a hobbyist, just wanting to find something that makes my hobby not quite so stressful.

To me, working with epoxy can be very stressful.

Alan

 

In general, about all epoxies which have long open times, need a postcure to reach optimum values. Luckily, a postcure cycle can be done relatively easy, especially in warmer climates (put black tarp or plastic around the object, and roll it in the sun). With some creativity, isolated sheets (I like the metal-foam-metal sheets) and some small heaters, one can do a good job easily.

If possible, gently heat with 10 degrees C per hour raise uptill the desired temperature, and keep it there for several hours (check datasheet for exact figures). But if sanding and painting still needs to be done, there is no real harm in just blasting away.

 

Thick Laminates

I have only infused thick glass laminates a couple of times, these have been the flanges on a catamaran cross beams and only 200 & 300mm wide.
I used a slow shade cloth for the resin transfer so that the resin did not race across the top too quickly. But there still was a large time lag between the resin front on top to bottom.
The thickest laminate was (450gDB/500gUDx4)6 total 14,700gsm.

What is normal practice for doing solid laminates, interlayer CFM amongst the UD?

Andrew

 

Some interlaminar CFM could help, but I do not like the stuff, as it creates a resin rich layer, and tends to trap quite some air. If doing that, please do degas your resin, and keep a vacuum on the laminate stack for a considerable amount of time. This seems to help avoiding bubble formation.

A question from curiosity: What do you guys pay for shade cloth? It seems utterly expensive to me.

 

Thanks Herman, when I did some test samples of thick laminates I found that even with no CFM it tended to trap air.

I use 30% and 50% shade cloth, 30% costs me $1.70m2 and consumes 320gm2 of resin, 50% is $2.45m2 and consumes 550gm2 resin.
Air Tech and Aerovac mesh is much dearer at $5 - 9.50m2.

Cheers
Andrew

 

Wow, quite costly. I am having my own brand of mesh, which comes a lot cheaper, and I will also check the prices for Airtech and Aerovac, as they seem way off of what I am used to. (I am Airtech and Aerovac dealer as well)

 

The proprietary infusion meshes are ridiculously expensive here, this is why most builders that are infusing use the grooved core.
So what are you paying for the mesh? shade cloth? in europe?

 

I would need to check, but for starters I checked the www.airtechonline.com website, which has a webshop, selling small quantity packages.

A roll of mesh (27 m2) costs 69 USD.

My own infusion mesh could be had for Euro 1,5 or so. I would need to check. Could be lower.

Shade cloth is not common here.