What Can Vacuum Bagging Achieve That Hand Lamination Cannot

All answers on the back of a self addressed envelope…

lots

Deabo, depends what yo are doing with it…

Other than that - your question…yawn…

imitate a good laminator?

Maybe I should clarify some more. I’m pretty sure that hand laminating is not an option for compsands but I believe it is for just straight stringerless. I also believe that Gordon Clark was quoted as saying that a good laminator can get pretty close to optimal resin to weight which is one of the benefits of vacuum bagging I believe.

I’m pretty sure that hand laminating is not an option for compsands

Why not? All of mine are.

But I have a love/hate relationship with VB.

Traditionally, the greatest benefit of vac bag’n is sucking out excess resin. There are other bennies and potential new ones. Low resin content can be achieved with hand lams, but ‘dry’ lams can cause slow leaks and surface finish issues.

Speed summed it up well…like so many other things, it depends.

Straight up foam( any type,) fiberglass and epoxy resin: The advantage would be you could do top and bottom at the same time and apply heat to cure it more effectively for optimal strength and weight while under vacuum.

I first was introduced to this technique 33 years ago. I am sure it wasn’t new then. The dominence of polyester resin is now gone and the pioneers of epoxy products for surf realated water sports have paved the way for neophites to dabble with all the friendly epoxy system and the applications of those materials. You can’t expect the “experts” of polyester to just be running with the epoxy believers at the drop of a hat. Change is very painful sometimes, so surfmag articles need to paint a picture of newness to vacuum bagging to keep everyone thingking we all are learning this new technique together.

lol

when whatever you are using as you composite matrix cures under pressure, it will have a more uniform and continuous crystal structure, resulting in a stronger matrix and stronger composite. I believe a hand lamination job could get the fiber-to-matrix ratio just as good as a vacuum bag, so I really think that curing under pressure is the only advantage over the best of glass jobs you could do.

you guys think that vac bagging can be achieved

with poly resin?

a small dosage of catalyst applied to a normal amount of resin for the size board and a brought down room temp?

i have been wanting to try the vac bagging with poly resin but am limited with my funds

that and i work in my back porch in FL where its always hot

i don’t think the other people living in the house would like it if i decided to do it inside either

what about the beneficial effect of compressing the weave in multi-layer lams? Not only does this help strength, but it reduces the little voids in the weave that need to be filled during the fill coat because the vacuum pulls the weave flatter. That should translate into less fill and less weight. Ok, marginally so. And, vacuuming would reduce the incidence of knocking the tops off of the weave as you sanded, which reduces strength.

Sure you can vac bag with polyester, boatbuilders do it all the time! Its only a matter of controlling the cure rate. Talk to your suppliers, I use a polyester that has an 8 hour cure time at 18 degrees C. OK it’s designed for infusion but tweaking the catalyst brings the cure time down and obviously increasing the temp’ speeds everything up.

There is definitely poly resin out there that will work fine in a bag. In my experience a vac bag will always produce a better result than a hand laminate but there is material wastage, fiddling and time.

the question is

define a better result

visible weave is not a better result

the market demands good cosmetics

A better laminate has fewer / no voids, consistant resin content, High fibre volume fraction, complete campaction onto the core / blank. Those are the basics. In my limited experience one still needs the cosmetic coatings.

I’m not suggesting that vac bagging is the ultimate laminating system (although infusion might be!), nor that skilful hand laminators cannot produce brilliant results, they do and I am full of admiration and not a little jealousy.

The ideal resin content for polyester resin is 55%. Epoxy is 35 - 40%. This makes bagging with epoxy very effective while with polyester your results will be dubious at best. There are reasons why polyester resin is not being used in high performance products. It’s just not as good.

If the ideal content for epoxy is 35 to 40 %, then how can anyone say that hand lams can come close to that? What am I missing. I ready to bag them all from here on out.

Note that the percentage is “ideal”. All you are doing with hand lamination and epoxy is using excess resin and therefore adding a bit of weight. There will be nothing wrong with the structure of the laminate.

Ive done hand lam test samples 2 parts fabric, one part resin, but not on surfboard foam. With the poreous nature of surfboard foams, it would be very difficult if not impossible to get that with hand meth. IOW, resin will fill the pores. As previously mentioned, at very low resin contents, cosmetics becomes an issue. G10 is a great example of smooth finish and low resin content. But they are done with prepregs and very controlled automated machinery.

I guess it really depends on whether you want to do the whole bleeder, peelply, breather show.

If that’s your game then you can get a nice clean outer lam. If you don’t then you will get an ugly visible weave lam with bubbles trapped.

My compsands currently our not outer lam vacc’d because the above. Hand lamming is not such a big hassle and gives an acceptable result with relative ease.

My recent forays into snowboard building are interesting in this regard considering the use of very heavy glass (750gr/m2!!!) and only mechanical pressure to laminate the layers. Most skis and snowboards are not actually vaccum pressed but hydraulically/pneumatically pressed. The wet out is manual and copious in resin, to achieve the ratios they want it is simply a matter of squeeze harder on the press. There some vac applications but not very many as they consider the pressure at an average of 20" HG to be inssufficient to get a resin/glass ratio they want !!! (20"HG!!!)

I guess pressure is pressure but I have always fancied the advantage of vacuum including low amounts of airborne moisture in the laminate. Considering what moisture does with reactive amine hardners, I am wondering whether this premise holds under clamped presses.

I know nothing about snow boards (except that I’d love to give it a go) but I do know boats and some research stuff.

I assisted in doing a resin infusion on a product that finished 25mm thick! We did it in both glass and carbon and it was done in one shot. Atmospheric, no more. So although one can throw loads of resin and glass into a mold and then apply huge pressure with hydraulics, it is possible to get a very high performance, massive, monolithic laminate without resorting to hydraulics.

Obviously low exotherm resins were used (epoxy) and some serious testing was carried out before the product went into production, but it was big you might even think wind turbine blade size!

Not sure of the point of this post, I seem to be losing it as the post work wine kicks in!