vacuum bagging - smooth finish without waste?

General Discussion
1

I’m trying to figure out how Mr. Burger gets an almost finished laminate right out of the bag.

Tried bagging a laminate with no breather or peel ply and carefully squeegee the air pockets out of the bag. It was nothing but a hassel and did not work well at all- with no breather in the bag the airflow gets cut off so that there is no clamping action on most of the laminate.

I’ve heard of perforated release film but also heard it leaves a little raised dimple at each of the perforations - certianly not an almost finshed laminate as these have to be sanded off. You have to put peel-ply over the perforated film and it seems like the peel ply would get consumed as the resin flows out of the perforations and into the peel ply. Also in the pictures Bert has posted the laminate surface looks VERY smooth with no dimples.

Please help figure out what the trick is? I am wasting way to many “consumables” and also too much resin. Sometimes the total cost of the consumables is equal to or greater than the cost of the laminate reinforcements. It’s just way too inefficent and wasteful.

What if I wet out the laminate on a piece of smooth plastic film, get all the air out of it, apply it to the core, then leave the plastic on and put peel ply over that as breather so that the vacuum can do its job?

So in the bag (from inside to outside) it would be:

core material

laminate

plastic film

peel-ply breather

vacuum bag

Only problems are :

I don’t think the film will go around compound curves at the rail - I think I need a film that is very stretchy to go around curves but also thick enough that it does not wrinkle too easily?

Doing a lap joint at the rails seems like it would be impossible because you’d have to lift the plastic at the lap so that the adjoining laminates would be in contact.

I’m having a very hard time finding a film that is both flexible and with a smooth surface - all the films I can find at local hardware stores have kind of a wavy, imperfect surface.

I am going to attempt to implement this idea as soon as my new batch of rr epoxy arrives - I’ve run out.

Also I think I need to get a better scale as it seems like the resin to reinforcement needs to be EXACT as there would be no place for excess resin to travel

Am I on the right track and just need to find the right film material or is there some other more elegant solution? Come on guys, many of you are very smart, if we put our minds together maybe we can figure this out?

Bert, can you throw a dog a bone here?

Trent

2

here is how i do my bottoms…

first i built a rocker table, the top is made out of a piece of formica that is waxed up with a dozen or so coats of mold release…

then wet out the outside glass on the rocker table, lay down the blasa skin, lay the wetout inner glass down, then lay the foam down… vac it at 15… inner and outer glass in one step… makes putting the rails and tail block on easy… there are a few pin holes here and there but the gloss coat gets those… i think with a heated postcure many of the problems will be solved…

bert mentions sespending your flexable bagging film on a frame…

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3

That sounds good. What weight foam are you using? Any distortion at 15 vacuum? Maybe I’m reaching here… what about the decks?

4

1lb foam… you need to distorate the foam a little to get the bottom smooth… think about it as the opposite of berts bottom contour pads, instead of concaves ete i am trying to press it dead flat… it took me about 6 tests to get it working how i wanted it to… again i think the post cure under vac will help a ton with any outer glass bagging.

i have done a few like this and then just layed up the decks by hand but i have a few things in the works to change that… chop chop chop goes the weight and resin usage…

5

Hey John

you doing the tube bag thing or are you taping plastic to your rocker table like in the windsurf video?

Seem like it would be harder to shove all that intoa bag versus just sealing the table with the board on it with plastic and vacuuming it that way.

I just did a double sided freehand layup shove into the bag vacuum the outer glass last weekend and it was one of the worse experiences in my brief sando life… Bottom glass peeled off when I flipped plus it started to kickj before I could get the deck on. Bubble wrap screwed everything else.

Using a rocker table with sealing tape and plastic sheets would be a heck of alot easier.

Looks like you’re also finishing the bottom rails after you lam the bottom on…

6

i use the tube bag and shove the whole thing, rocker table and all, into it… having both ends open is a huge help… i hate the sealent tape, spent more time messing with it then i care to remember… the best i could do was getting the pump to cycle every 5mins… with the tubes i can get it to around every half hr… i use the cheap nylon ones from [/url]http://www.acp-composites.com/acp-vbes.htm[url], the quick clamps are nice and easy also…

the next thing i do to the board in the photo is cut out my outline and then bag on the rails… the biggest trick i have for the rails is being sure that they extend past the bottom… then i grind them flush with the bottom roughing up the bottom glass so the top glass will bond as i go…

7

Airtech offers Stretchlon in a tube form. I don’t know if they sell it by the foot though… The flat material might be able to wrap cleanly around the rail if the blank is on a recessed elevated riser on top of a rocker table. The stuff is supposed to stretch 400% - 600%. That’s quite a bit.

My rocker table will be covered with 6 mil polyethylene “bamboo rhizome barrier” I can buy at the local nursery by the foot. I can get it in longboard lengths for a seam-free table top.

http://www.airtechonline.com/whatsnew/index2.htm

8

To get the best possible finish on a bagged laminate, you need to peel ply the product first. (You need enough excess resin to totally wet out the peel ply) Then you apply the perforated film over the peel ply. Then the bleeder blanket.

The perforated film stops the blanket sticking to the peel ply, and allows the air to be transfered from the laminate to the vacume hose via the blanket.

The perforated film and blanket can be used a few times depending on how much resin the blanket absorbes.

Unfortunately there is alot of consumables wasted in the vacume bagging process. I guess it is the price you pay for having a strong and light product.

"What if I wet out the laminate on a piece of smooth plastic film, get all the air out of it, apply it to the core, then leave the plastic on and put peel ply over that as breather so that the vacuum can do its job? "

If you do what you describe above. Any air caught under the laminate will not escape because the plastic does not breath. Peel ply is not a breather. It is designed to absorb resin, act as a release agent, and to provide a finish (when pulled of the product) that does not need any sort of prep prior to the next laminate. Apart from some sanding along joins and removing any strands left behind. Having said that. Most of the people I have worked for who do bagging work, do hand sand the peel plied surfaces prior to laminating.platty.

9
Quote:

Unfortunately there is alot of consumables wasted in the vacume bagging process. I guess it is the price you pay for having a strong and light product.

I understand the “standard” basic vacuum bagging process with peelply and breather and have been doing it for a few years now.

Incedentally perforated film is usually used right against the laminate so that in the bag you have (from inside to outside):

core

laminate

perforated film

peel ply

breather

The result is a relatively smooth laminate with little dimples at each of the perforations, and lots of waste!

One of Bert’s recent posts claim that the “standard” process is some kind of scam to sell lots of consumables.

I agree that the standard process is inherently flawed. You need to put on excess resin and then the standard process ALWAYS removes too much so that the weave of the reinforcement shows through. In addition, with the standard process (peel ply against the laminate) the peel ply ITSELF leaves a texture on the laminate which needs to be filled.

I want to somehow get around these flaws and get a finished or nearly finished surface right out of the bag.

The reason I was thinking of using peel ply over the plastic film instead of a regular breather is that the peel ply is much closer to being a smooth surface than the polyester batting typically used for breather.

If it doesn’t get saturated with resin, peel ply should work fine as a breather.

I understand that if I try this I would need to pay close attention to the resin/reinforcement ratio, as well as pay close attention to getting all the air out from between the core/laminate/plastic film.

Just from what JJP has shown in his posts to this thread, what I am thinking should work, I’d just be replacing the waxed rocker table with a plastic film.

I’ll do a two step baging process so that small amounts of ecxess resin/air can travel to the edges of the film. The Stretchlon stuff mentioned by John Mellor looks like it will work well.

My resin did not come in yesterday, looks like I will have to wait untill monday at least.

Trent

10

Peel ply is a sealer isn’t it?

don’t you want your resin to seep out to the blotter?

There’s a paint drip blotter at HD thats has absorbant material on one side and smooth sealed white plastic on the other. But you can’t see through it.

Good to go over the perfed layer and in between the bag and it’s breather material

I don’t know if I’d ever do both sides at the same time again though without two people…

11

stoked to read about your work jjp!

man were u guys bin?

meaning all the ‘j’s’

12

If you are using peel-ply outside your perforated sheet, then you are just wasting peel-ply. Peel ply is meant to go directly on the laminate, so when cured, can be peeled off leaving a prepared surface for further laminates, or a filler coat.

Unless you want a perfectly flat bottom vacuumed directly onto a flat rocker table, the trouble you would have to take to avoid sanding is not worth it. The sanding on a good vacuumed product is minimal anyway.

Actually a sanding free board is possible, takes quite a bit of time and preparation, and it’s called a mould.

13

http://www.advcomposites.com.au/prod02.htm

Trent. I was only trying to give you the benifit of some of the 25 years experience I have had working in the composite boatbuilding industry. No body that I have worked for puts the perforated film directly onto the laminate. The process that I described is the industry standard. I admit it is wastefull. But in the long run, the product, if made properly should last much longer so you will save money in not having to replace your surfboard every six months.platty.

14

I guess I had it all wrong Platty. Your years of experience far exceed my own limited experience and research. Please forgive me If I have offended you.

Trent

15

Pages 2 - 8 of this 10 page newsletter show a foam wing tip being bagged. They make mention of the fact that the bag wrinkles have to be sanded out after bagging. The article also shows the different consumables being used and a cheapo autoclave for heat curing the epoxy.

http://www.eaa1000.av.org/newsletr/0305nltr.pdf

16

Trent. Are you bagging a laminate onto your blank ? Or are you bonding a timber skin as shown in one of the photos above? I sounds from what you are saying, you are doing a laminate only. As you mention rapping the plastic around the rails. If this is the case. Would you not be finishing the board with some sorf of paint system? Or have you painted the blank? platty.

ps no offence taken.

17
Quote:

Peel ply is a sealer isn’t it?

don’t you want your resin to seep out to the blotter?

No, I think the idea behind peel ply is that it doesn’t stick to epoxy, and although the weave is tight epoxy will seep through the weave and into the fibers of the peel ply removing excess epoxy and leaving a textured surface for a good bond for the next layer…

regards,

Håvard

18

I was thinking about using wax paper then taking a dry roller to it before putting the whole thing in the bag, i think this would eliminate the wrinkles and would easily peel off. Pretty much the same idea as peel ply, but a cheaper version. I think I could probably get it into the concaves without the wrinkles, but I would doubt the rails. What do you guys think, anyone do anything similar?

19

jjp - killer stuff. That’s what I’ve been shooting for, and not quite getting there. No rocker table, that’s probably the biggest difference.

For the smoooth finish, I think you’re counting on the excess resin being pushed into the balsa or the blank, rather then sucked out of the cloth, through the peel ply, into the absorbent. That said, you’d want your vac tube attachment on the bottom of the board, with shade cloth, if you were working your deck lam (or on the deck if you were working your bottom lam). The trick would be to start to pull vac & shut down around 3-5 InHg to pull the wrinkles smooth on the side you were laminating. You couldn’t do both sides at once like this (without the consumables) because you’d have to pull all the wrinkles down to the opposite side of the board as the lam is on.

Even with the consumables, I shut down at low vac & straighten out my bag. Its also a good time to tweak rocker, remove twist, etc…

Ready to bag - balsa, both inner & outer glass, tools, peel ply, absorbent, shade cloth, bag…

One layer of glass wet out - 10’ x 2’ of glass with 8 oz resin & 2 oz hardener…

Peel ply coming off:

Up on the wall in the shop:

20

Hey Ben

sorry for the stupid questions but this has been bugging me for awhile now…

But what the heck is “shade cloth” exactly…

Blue tarp?

Heavy canvas for paint drips?

or something else?

I’d like to give it a try versus the standard fiberfill batting I’m using as breather…