Resin Infusion, the next step?

I recently used resin infusion to make a longboard, fiddly but fantastic laminate. I put a posting on Magic Seaweed and attach the link, however I have a full description and photo journal if anyone’s interested?

http://magicseaweed.com/surftalk/viewtopic.php?t=6551

I am interested, please post those photos and any comments you would think about. I only did small tests with infusion, but had a lot of technical discussions with professionals who handle infusion very well. Any information on how you did it for a surfboard would be interesting, I have all the theory worked out for this particular task, but your experience is probably invaluable.

Howdy…I also would like to view your full description…thanks.

Nice work Rikds!

I’ve also been experimenting with resin infusion. I like that you infused along the width instead of the length. Did you have to use more than one resin input port?

I was also wondering what kind of foam you used and whether you sealed the foam before infusing. And also what vacuum pressure you used. My experience is low density EPS sucks in too much resin. Also the case with low density PU. XPS, of course, works great. I haven’t tried sealing low density EPS yet so I’m hoping it’s a good solution.

I’d love to see how the resin infusion is controlled, if you could post some pics, thanks

Thanks for the messages, glad it was of interest.

Several questions which I’ll answer in no particular order.

The blank is PU from Homeblown. I did not seal it before glassing. As it is close celled it does not adsorb much resin. In fact the only cells that can adsorb resin are those “opened” by sanding. Infusion theory says that if you suck all the air out, the voids left will be filled with resin. This seems to be the case as I did some microscopic studies on test panels and found no unfilled voids / cells.

There is one inlet point but this feeds into a tight “roll” of distribution mesh running the length of the board about 2-3 inches from the rail. This filled fairly quickly with resin which then fed across the board, top and bottom, through a layer of mesh. Suction was done the same way. However I did stop the mesh too far from the suction edge and allowed the peelply to complete the suction / infusion. This slowed-up the process. Fortunately I was using an 8 hour geltime epoxy (taking no chances!) and the whole thing went fine. Once the resin is into the catchpot, the feed line is closed and the vacuum left on until it has cured. Unfortunately these slow hardeners result in a resin that needs post curing, so I cooked it in an oven for 8 hours at 50 deg. C.

Again theory has it that the mesh should be stopped “ the thickness of the laminate from the laminate edge”. Next time I’ll be braver.

The question about controlling the process frightens me! Once the bag is pulled down and the leak checks are made, the valve is opened and the resin flows. Apart from praying there is little to be done at that stage, what control are you looking for?

My pump pulls down to 0.8 bar and this is plenty adequate. It might crush a low density foam like EPS, you’d have to experiment.

The biggest problem (and it is BIG) is ensuring that the laminate stack has no slack in it when the vacuum pulls down. Any slack cloth will result in a crease somewhere. I got a small one on the rails. The problem is that although the tack spray works well it is not perfect. I controlled the rate of evacuation with a bleed valve and tried to smooth the layup down as the air was removed and once happy closed the bleed valve and pulled full vacuum. One way round this might be to seal the blank and infuse the bottom and the rails sealing the bag to the top. Then reversing the process. Cunning at the overlaps and the use of peelply will result in laps that need no sanding and the textured finish will be lost in the flowcoat.

There are some more photos at this link, view them as a slide show.

http://www.photobox.co.uk/album/3882842

Hope this is of interest, please get in touch for more discussions. I will be doing more like this and hopefully refine the process.

Thanks Rickds, I was over complicating it trying to think the process through in my head. Where did you source the peel ply and membranes etc…

Is there a website for that stuff in the UK?

Hi,

try Tygavac they do everything or Matrix Mouldings in Bristol,

Beware those wrinkles!

Rik

Hi Rik,

I was wondering how you keep the big pot of epoxy from getting too hot? Is it because the vacuum pulls the epoxy really fast and has no chance of getting hot or do you cool it somehow? Thanks.

Cheers,

Rio

It’s not that much resin in the pot, just a big pot! Using a 12mm diameter inlet pipe gets the resin moving pretty quick. Also it was a very slow hardener so the whole process only produces lots of heat as the geltime is approached. I actually took the leftover resin (still plenty fluid) and stuck it in the deep freeze for a few days. Took it out and allowed it to warm up. It became fluid and cured later in the day. This is the basis for prepreg materials.

hi Rikds, what epoxy did you use,is it low viscosity and uv stable and what was the cost , thanks, pete

Great thread, thanks for sharing.

Interesting stuff Rikds.

I was wondering why you started infusing in the first place.

Can you summarize the benefits of infusion as it pertains to surfboards?

A really superb low viscosity epoxy (RS-L285) with a slow hardener from PRF in Dorset. I don’t think any epoxy is really UV stable although Sicomen (France) make one especially for boards supplied by Matrix mouldings in Bristol. The hassle is the post cure. I had to build an oven (builders insulating foam 100 mm thick with foil on both sides, be sure to insulate a concrete floor as it is a huge heat sink), various heaters were used and a fan to ensure reasonably even circulation of the hot air. The temperature was raised slowly to just over 50 deg C and it was held for 8 hours and allowed to cool. Properties of the epoxy improve enormously. UV protection gained with 2 pack polyurathane varnish.

Mainly coz I like the technology and have the equipment to try this stuff, but also I hate sanding, especially the laps. If all goes well using this method there is minimal sanding and a very uniform finish before flow coating. From a technical point of view one also gets a higher fibre volume fraction (more fibres and less resin, although the fibres are the same as a hand layup it is actually the resin content that is reduced!), this should mean a slightly lighter board. I’ll weigh it and you can compare it with other 9ft boards. It also results in a board with absolutely no voids but I know you whizz laminators can hand laminate with no voids but they can be a problem for us less talented types and so I rely on technology!

I’m not suggesting that it is the best or quickest way to build a board, just another way…And it can be done with polyester just as well, it is just more difficult to control the gel time…

Another reason is that the whole process is over in one go. No laying up the bottom, waiting for it to cure, blending the edges, turning it over and laminating again. No sticky work dripping resin around the place, no clean-up, minimal fumes, no rubber gloves…it really is a clean process! OK there may be more resin waste in the pipes and mesh, I probably scrapped more resin than ended up on the board and that can be costly but with careful record keeping exact quantities can be calculated and repeat operations use only the amount of resin required and none is left in the bucket.

It’s a mixed blessing

I am very interested in vacuum infusion, my next board will be done that way, hopefully it won’t be a throw away! A few questions:

After removing the peel ply how much “print through” texture was on the surface of the board from the distribution mesh? Or did it not print through the peel ply? Basically I am curious to know how much finish work is needed to get a smooth finish (assuming you don’t have loads of nasty wrinkles), e.g. any fairing and sanding steps, or just a sanding coat then gloss coat, or no sanding coat, etc.

Also do you have any good links an vacuum infusion you used for researching this process? I’ve found good info at http://www.fiberglast.com, but I still haven’t found a way to calculate how much resin is needed with the distribution media and tubing, which obviously will vary depending on what media is used

Thanks

Mike S

Quote:

I recently used resin infusion to make a longboard, fiddly but fantastic laminate. I put a posting on Magic Seaweed and attach the link, however I have a full description and photo journal if anyone’s interested?

http://magicseaweed.com/…viewtopic.php?t=6551

Hi Mike,

Mesh print through was not a problem, although it might depend on the mesh you use. Mine was pretty fine but had a good “loft” under the bag. Where are you? I could send you a sample? I found that once the peelply was removed the finish was terrific, all I did was paint on a layer of epoxy, sand it fair with wet & dry, then put 2 coats of 2 pack polyurathane varnish on the board to give it some UV protection. All in all its great however in some light I can see the stringer appears a little proud of the foam (it is very little and only shows in some reflection), this is obviously a result of the ply being uncompressable compared to the foam when the bag is pulled down.

The only way to accurately work out resin requirements is to do some test panals. I found that when the resin was about to run out I clamped off the feed line between bucket and bag, mixed some more resin, poured it into the bucket and opened the line again, no worries.

Possibly the most tedious part of the operation was removing the peelply/mesh stack, it took a lot of experimenting to come up with the “spam tin opener” technique!

Let me know if you need any suggestions…

Cheers

Rik

Thanks for the reply, glad to hear fillers and fairing can be avoided if I do it properly.

Quote:

Mesh print through was not a problem, although it might depend on the mesh you use. Mine was pretty fine but had a good “loft” under the bag

What flow/distribution media did you use? I see that Tygavac’s website looks alot like Airtech’s, and they sell a few varieties. I could probably buy the same stuff here in the US.

Quote:

the stringer appears a little proud of the foam (it is very little and only shows in some reflection), this is obviously a result of the ply being uncompressable compared to the foam when the bag is pulled down

How much vacuum pressure and CFM do you really need for vacuum infusing surfboards? My little vacuum pump is rated at 1 cfm and I’ve been able to pull 25" Hg or so. I just need to determine if it’s up to the task

Thanks again

Mike S

The mesh I used came from a UK manufacturer called Newbury Engineered Textiles in the UK. Tygavac and Airtec seem to be the same outfit, the latter being the US company, they will have everything you need. Give them a call, these companies have technical people who seem to love discussing projects and problems!

My pump is small and also pulls 25"Hg. I’ve built 21ft foam cored racing yachts with it so you will be fine. The trouble is always “how much suction does one need?” My feeling is “enough to do the job”.

What we tend to do is lay everything up dry , bag it and pull full pressure for about half an hour. When the infusion starts one could back off the pressure a little so long as the resin still draws, as far as I can see there is no reason to maintain full pressure while the cure takes place. Obviously one will use a little more resin and gain a little weight but it will be negligible.

any help?