Vacuum Infusion questions

[JohnC]

I saw a couple of builds on the other forum that used infusion to build from the hull up. It looks to be very stiff & light-weight. I'm intrigued! I would like to make some parts this way and I have been doing a lot of reading and watching videos on the subject. It looks doable in a garage with a small investment in equipment. I have a vacuum pump but I need the hoses, trap, fittings and some specialized consumables (vacuum film, flow medium, peel ply). Building molds seems to be the biggest part of the work.
I was wondering about the best core material to build a console & hatches. PCV foam, polyurethane or polyester? Most things I have read say PVC for structural and PU for insulation but I'm not confident in that. The stuff I have read doesn't recommend a density of foam core either.
I also don't understand if its best to do a gelcoat skin and CSM and let it cure, then setup the infusion on top of that or can do it all at once. I plan to do some small parts as some trial and error would be needed.

Has anyone done any infusion projects on this forum? I did a quick search and didn't see any projects with pics. Any help or input is appreciated.

[Bigshrimpin]

I haven't done any, but I am also interested in experimenting. Metan has a few videos doing vacuum infusion. I think it probably doesn't make much sense if you are just re-coring a hatch or two. if you want to be fancy, you could just vacuum bag them. There are a ton of youtube videos on the subject.

As far a core goes . . . Most floors and hatches are cored with using scrimmed foam core like corecell or airex which is 5lb density PVC foam.

[FLexpat]

I have been playing around with vac infusion a little (small stuff) to learn how I can use it for the deck on my 23. So far I have just done a few small experiments but they have pretty much convinced me to use VI for the decks and some transom stuff. When I get a chance I will put together a writeup and post it but I still have a lot of learning yet to go.

I learned a TON from this thread: www.boatdesign.net/threads/infusion-plan.43380/ It is definitely worth reading several times - I took lots of notes every time I read it.

My original plan was to use epoxy but now i am using a low viscosity VE infusion resin. I am using double cut 3/4" Corecell as the core. The Excel spreadsheet I am using to figure all this out is WAY out of control...

[flyingfrizzle]

I have also used a Low Viscosity Hydropel VE infusion resin from AOC when I played around with it. Bought a full 55 gallon drum left over from a hard top going on an Hatteras. Having a low viscosity resin is a must. Most infusion resins are low growth which helps also. Far as your question, I found out it was better to do the gel coat and let it harden first or you can get print threw from the cloth. AOC list a specialty product that claims it can be used on wet gel with low print threw in their brochure though. I found that by time you spray or roll the gel coat and prep for the infusion the gel will be cured enough to continue. It cures enough in 30mins to an hour to be ok to lay up over. It is kinda hard to find VE based gel coat but its out there. I ended up doing it over poly gel and it worked ok. Most of the stuff I done I didn't use gel at all as the AOC resin I had was designed to cure out white for easy paint coverage (long as you use clear mekp). I just waxed the molds and did it all in one shot since the resin cured almost as white as gel plus I was painting the parts anyhow.
On the core to use, It depends on the use of the part. I have had core cell with holes drilled on 1" squares to let resin and air pockets pass. The core material I have currently has scores on both sides in opposite directions mainly for forming curves but it aids in letting the resin flow as well.
I found the infusion consumables to be expensive but found some more affordable options such as using spiral plastic wire protector for flowing the resin and plastic foils from my ol lady's work for bagging. I also found that the metal roofing seam tape works well for sealing the bag and appears to be what they send you anyhow just at twice the cost or more. I found out the hard way a few times how not to do it but here are some helpful tips that aided in helping me:


I used a large shallow pan to draw the resin out of to slow the cure time.
Done the infusion while it was rather cool in my shop then closed the doors and kicked up the heat to cure.
Had extra resin on stand by that I could kick and then to add to the pan if I was running low.
Try to not mix hard to introduce air bubbles in the resin and let it sit to gas out the bubbles.
Make sure I had plenty of routes for the resin to evenly cover the entire part.
Have a pump that will pull plenty of vacuum.
Make sure the bag will actually seal up well.


You can learn a lot more from others as I have only figured out a few things the hard way and have a long way to go to be good at this. I found it much more easy to hand lay the cloth and resin then bag it and draw vacuum but then you are not infusing the resin then.


I will attach a link to the resin I used...

[JohnC]

Thanks for the advice. I will check out the boat design link an Matan.
I was going to use straight polyester resin for the parts I am making - I will probably botch a few parts at first so cheaper is good. I didn't think there would be a great advantage to making a console and hatches with vinylester but I may be missing something. I am doing epoxy for any secondary bonding where needed and the stuff I am making is above the water so no worries about water intrusion. Are there other advantaged to VE resin? Please let me know if I am missing something - I have never used VE and I don't have much experience with this stuff.

I too have thought about doing my deck with VI but I wanted to start small to see if I could pull it off. That seems an ambitious project. I lightweight monolithic deck would be pretty cool if I could pull it off.

[erebus]

Quick primer from being in the boat repair business for 15 years.
I'm sure one of the guys with more technical knowledge will point out where I'm wrong.

For making new parts polyester is fine. Polyester has terrible secondary bonding characteristics, so not so good for repairs.

Vinylester is a polyester modified with epoxy molecules. Has excellent secondary bond characteristics, and can be used to make parts, but the benefits are negligible over polyester. shrinks less than polyester, so that might be a plus in part making. Has about a 500 PSI tensile strength.

Epoxy is very strong and completely waterproof. Polyester not so much, Vinylester is somewhat more waterproof than PE but still not completely.
Epoxy can have about a 2000 psi tensile strength. Strong stuff. And expensive!

[flyingfrizzle]

Originally Posted by JohnC

Thanks for the advice. I will check out the boat design link an Matan.
I was going to use straight polyester resin for the parts I am making - I will probably botch a few parts at first so cheaper is good. I didn't think there would be a great advantage to making a console and hatches with vinylester but I may be missing something. I am doing epoxy for any secondary bonding where needed and the stuff I am making is above the water so no worries about water intrusion. Are there other advantaged to VE resin? Please let me know if I am missing something - I have never used VE and I don't have much experience with this stuff.

I too have thought about doing my deck with VI but I wanted to start small to see if I could pull it off. That seems an ambitious project. I lightweight monolithic deck would be pretty cool if I could pull it off.

I use a lot of poly for molded parts, especially the ones with gel coat base. Just from what I have seen most infusion is done with VE and most infusion resins I've seen are VE based. Im sure there are thin viscosity polys our there that can be infused but most people seem to use VE for infusions. May have to do with the structure of it and the low shrinkage.

[JohnC]

I watched a few of the videos on the Metan site and learned a few things. It looks like they buy rigid foam sheets and score & perf them. that's a little cheaper. It doesn't look like there's much precision involved - just a saw and a drill. They also bag under the layup on the table and use weights at the edges to keep it flat under vacuum. I assumed that I would need to draw it down to a rigid form. Some of this is minor stuff but still good to know. The whole think looks like redneck arts & crafts.

I noticed that the Metan VI includes keeping the vacuum on during infusion. Some of the videos I have seen from suppliers show a layup under vacuum and then the existing vacuum draws the resin in - no pump running when the resin goes in. I just assumed the pump was there to hopefully salvage the part in case of leak. Is there a right way? Why?

Thanks for the resin summary erebus. That's kind of what I was thinking but I wasn't sure. I have never seen it summarized enough for my attention span.


I haven't found thinned VE or PE but I haven't looked very much - I am sure I will find it. I'm near Ft Lauderdale so if its about boats they sell it here. I read that styrene can be added to PE (not sure about VE) to thin it but I didn't see much about how it affects the strength. I imagine it would have to diminish the strength of the resin if 10-15% of "not resin" were added. Maybe someone else would know more about thinning.

[flyingfrizzle]

Originally Posted by JohnC

I haven't found thinned VE or PE but I haven't looked very much - I am sure I will find it. I'm near Ft Lauderdale so if its about boats they sell it here. I read that styrene can be added to PE (not sure about VE) to thin it but I didn't see much about how it affects the strength. I imagine it would have to diminish the strength of the resin if 10-15% of "not resin" were added. Maybe someone else would know more about thinning.

Most infusion resins would be a special order item I would think, I purchased mine from a shop that was doing infusions. They had an extra drum to sell at half cost but was willing to sell me by the gallon as well if I only need a small amount.

I lot of people just buy standard resin and thin it. Styrene works both with PE and VE and I have even used acetone to thin but recommend styrene. Just keep it under the recommended percentage. Each resin manufacture has one but most fall around 10-15% like you mentioned.