Infusion Q&A

[CatBuilder]

25"+ for infusion. 20+ for good bagging

[Herman]

You can infuse at 17, but you run the risk of haziness, which is what you want to avoid at all times. Really, unless you do everything you can to avoid haziness, I would strongly suggest doing this by hand, and practice infusion on less critical stuff.

Things you can do:
-preheat resin
-degass before and after mixing
-do a very proper leak test, no leaks allowed at all (which can be hard on a boat hull)
-infuse in heated mold (120F)
-infuse at as low a vacuum as you can get.
-before infusion, make sure your materials are dry to the bone. (wood is difficult)

[jim lee]

How different is infusing epoxy as opposed to say.. vinyl ester resins?

-jim lee

[Herman]

There is not much difference. Basic setup is the same.

Epoxy:
Long open time. Does not suddenly cure. takes a long time to cure properly however, and also the sometimes hairy time between completing infusion and cure is longer than with VE.
No fiddling with additives. Just resin and hardener.
Try and achieve a good mixing. Is more difficult than with VE.
Usually slightly higher viscosity. Longer infusion time.
Less shrinkage
Needs postcure in most cases

Vinylester:
-curing speed can be taylored with additives.
-faster final cure
-does not need postcure, although postcuring helps achieving a better cure rate.

[jim lee]

Thanks Herman, I ask because we use vinyl ester now and are thinking about switching to epoxy for a few bits. Wondering what hidden mine fields were going to stroll into this time.

P.S. Herman, your in the Netherlands. Odd thing about The Netherlands.. Our stereos are getting popular there faster than other places. I'm wondering why The Netherlands? You have something to do with this?

Thanks!

-jim lee

[Herman]

Your pitfall? Perhaps gelcoat.

About your stereos: no idea why they become so popular in Holland specifically. Looked into it, and it is a very neat little product, very clever. Especially with the USB charger. My father-in-law got his brand new Volvo delivered today, and guess: a connector for an iPod/Shuffle/whatever in the box below the armrest, (line in) but no USB connector! OK, you can plug the car charger in the cigarette lighter, but that is not as sophisticated.

Anyhow, I will keep the "Simple Stereo" in my mind, and perhaps generate even more sales for you.

[tunnels]

Originally Posted by Chieftain

Thanks Herman, but your answer leaves me confused. How much vacuum would be necessary to infuse it?? And if 17" of vacuum is not enough for infusing, is it enough for just bagging??

Can you give me some pressure ranges to work with??

The vac for bagging is related to doing the job to get what you are wanting , every panel is differant, every situation is differant from the last . There seems to be no actual pressure setting . The lowest i have used is 2.5 psi on a pressure gauge .and the panel was 10 mtrs long and 2 mtrs wide BUT the core was only 20 mm thick . with 2 layers of 800 gram biaxl glass each side !. This was one of the small panels we were into at the time !.
Bagging at high vac can creat more problems than it solves , things happen under cores and out of sight that you cant see ,so try exsperimenting on a clear sheet of thick glass to understand thoughly what you are doing, and what can and does happen at differant pressure settings .Max vac is not what you need ,little is sometimes better .
I am no expert and do not profess to be one ever , There are hardly ever yes and no answers ,just lots of mights and maybes !! we are really all students in the field of compostites and when you think you have all the answers some one will come along to prove you wrong !! .
Herman is the infussion man .

[Fgayford]

It could be that you are not degassing at a low enough vacuum.When you first see the off gassing bubbles you are not at enough of a vacuum. Go to near absolute vacuum and it should speed up greatly. I think I got this information from the Freemans instructional DVD. They said you do more harm with a low vacuum than not degassing at all.
Fred

[Herman]

Hmm, degassing at half vacuum indeed is a waste of time, but harmful?

[groper]

Hi, i am wanting to infuse a double skin and core layup in a mold and have some questions/concerns about core placement. The plan is to use perforated foam core with transfer media over the top.

The size of the layup means i need to use many pieces of foam core material and im concerned with all the joins in the core becoming paths for race tracking, and leaving me with dry areas... do all the pieces of core need to be joined with bog prior to infusion, or can the cores simply butt together tightly and let the infusion resin bond them together during the infusion?

What is the maximum allowable gap between core material if you cannot achieve a perfect fit between each piece?

[Herman]

Any gap will cause race tracking. Join the pieces with 5 minute epoxy or even PU glue, or lay them tightly and fix them (composite staples are nice for that).

Or make sure the race tracking paths cannot spoil your infusion strategy. In other words: design them in.

[sunbelt57]

To avoid the problems with pulling a vacuum on the balsa or wood bulkheads would it be feasible to install the wood supports after the fact by gluing them on? Or putting another layer of laminate over the wood supports but just doing regular layup?

[Herman]

I am not sure if I get the message, but yes, after infusion of the hull, it is no problem of installing the bulkheads later on, by hand laminating.

[groper]

Ok heres a question, ive been given conflicting information on when to clamp off the resin lines near the completion of the infusion...

Some people have said to clamp off the resin line when the part is still only ~80% infused, as the remaining resin in the laminate will finish the infusion...

Another person has told me not to do this and only clamp off the resin lines once the part is completely wetted out or i could have starvation problems...

What is the correct procedure when infusing thin laminates, approx 600-1200gsm each side of a perforated foam core?

[CatBuilder]

When you wet it all out before the shut off, you wind up with more wasted resin in the trap than if you shut off early. I don't mind the wasted resin, when compared to the possibility of an incomplete wet out.

This is more of a personal preference, which is probably why you are gettin conflicting answers.