After seeing a few vacuum-bagged boards by posters here (Mr.J and Bert Burger come to mind), I attempted to research the process (just got more confused!) and tried to wrap my head around the following two thoughts/questions:
What actually happens during the process (how do the resins/cloth/other materials “behave”)?
What are the advantages/disadvantages of each technique concerning the finished product (in other words, which of the final products is better, not which techniqe is more of a pain in the rear)?
Well, “better” depends if you want a finished board with the least amount of time involved in the building process, you are satisfied with the weight, and you are not introducing skin layers such as wood laminates, coremat, Divin/airex, or honeycombs.
Or, does “better” mean you want the lightest, least possible resin to glass ratio, highest possible tech, in theory most reliable for weight, and lightest weight board you can possibly make, regardless of technology.
Say a 9’ log. First paragraph makes a 12 lb’er minimum, that is still as strong as poly glass 16 lb’ers.
Second method, vacuum, gets you easily a 9 lb’er, more dingproof than poly glass 16 lb’ers.
I only use the vacuum process to get the sandwhich material (pvc) to stick down to the blank. I have never vacuumed on the outer layers as…
I don’t want to spend the extra money for peel ply and bleeder material which gets thrown away.
I don’t want to spend the extra time I figure i’ve already laminated the board and it’s extra labour putting on peel ply, bleeder material and then putting it in the bag for hours.
I am concerned that I may pull out too much resin and then the board will be weaker. I have been told the board will be just as strong but lighter but i still can’t get my head around that.
I welcome any comments to change my mind and convince me to vacuum bag the outer layers
Just curious, why would you throw peel ply away? Save the step and use non porous release film. It is reusable if you set up your bagging schedule proplerly.
I thought that the peel ply(looks like suit linning cloth) lying ontop of the glass would absorb some of the exess wet resin (reducing the weight and increasing the glass to resin ratio)which would then go hard, so it can’t be reused again.
Tell me more please about non porous release film I’m presuming its a plastic film, does it crease? does it trap air between the glass and the release film?
Porous vs non-porous? I thought the porous peel ply allows excess resin to flow through the pores and be absorbed by an absorbant blanket material that gets tossed out. Some peel plies are non-porous and designed to give a more finished surface. It’s available in various materials that may or may not be reusable.
Non porous release film is normally used on top of your bleeder cloth to prevent you from sucking out all the resin thru your bleeder and into the breather material. If you want all the resin to stay in the wet out cloth then omit peel ply, porous release film & bleeder. In my opinion in order to get the proper ratio( resin/epoxy to cloth), one would need to figure out what the appropriate bagging schedule would be ( IE, How much bleeder material to use for appropriate resin 2 cloth ratio).
I reuse my release film — porous and non-porous. It’s pretty durable. For breather/bleeder material I’ve used several layers of paper towels. It works.
Unless you are using pre-pregs, you must use a release layer and a breather layer when vacuum bagging a surfboard. If you were to use just the bag, the vacuum would get cut off before it reached the whole length of the board. The breather allows the air to escape evenly along the whole length.
These guys did a great job explaining the vacuum bagging process (for snowboards) going through several different types of presses/molds and how to build them. Check it out, if you’re still confused.
As Lee said, unless you’re doing something tech, like laminates or wood or something, the only real benifit is from strength and weight. I’ve read that the ideal mixture of resin and fiberglass is 50/50, and that vacuum bagging is the way to acheive that. Additionally, less resin means less weight. But now to put it into reality… how much stronger and lighter, and is it worth the trouble? For most of us, probably not.
