Vacuum bagging procedure

[runpasthefence]

Hey guys,

I've been working a boat that I've been building a custom pad on for the past few months. I'm a newbie when it comes to glasswork, so a friend of mine in the fiberglass/boat painting business has been helping. However, he's been too busy the past few months and now I have a boat upside down in the shop and Spring is here.

Anyway, I've got the pad formed up on the boat, I just need to build it up with glass. In effort to make better 90 degree angles on the pad, we had planned on vacuum bagging the glass onto the pad. I still plan on doing this, however, I need a few pointers.

First, what type of glass should I use? I was thinking about using chopped glass for the first layers then going with the chopped/woven combo stuff for the top layer. Also, what thickness?

Second, how much should I build up, or how many layers? I suppose this is relative to the thickness question.

And lastly, when vacuum bagging, should I wet and lay up all layers at once, or is this a step by step process?

Thanks in advance,

Mick

[RBT]

Vacuum bagging and Vacuum infusion are two totally different process's.


Vacuum bagging is used with wet material, then covered with peelply and an absorber, breather membrain, and then the bag. The idea is to give even clamping over the work area.
The upside, no air bubbles, no excess resin....... downside you can acutally draw out too much resin...... you need the right vacuum pump for the job.

Infusion is with dry material. There is more art with this process. You lay up everything dry, cover it with peelply, then a breather, then an absorbant, then the bag. You place it all under big vacuum... like 30 inchs of mercury. Then you allow the vacuum to pull in the resin through predetermined locations. Upside is a lighter, stronger product with lower fumes....... and a few other benefits...... downside you better know what you are doing as if you screw up.......... you loose your part.
Most guys that infuse keep it pretty guarded as to exactly how they do it, Sharky is fairly open.... the other guys I know arn't. I am infusing my hull this week... it is the best modern method of building.


RT

[Riverman]

I think that in an uncontrolled eviroment with little experience it's better not to try bagging. Wet layup is easy and striaghtforward, with bagging you could end up with a BIG mess.

[RBT]

What he said

[runpasthefence]

I'm doing a very basic vacuum bag layup, not no infusion involved. Just as RBT suggested, I'd doing this ensure uniform compression, especially around the edges.

I have all the right equipment, it's just the materials and the process that I'm fuzzy on.

I think we've established that all of the material is layed up at once. What about the type/thickness glass I should use? Any ideas?

Mick

[A Fn Noob]

http://www.fibreglast.com/documents/361.pdf

[A Fn Noob]

Sorry thats not the link I meant to post. Theres a chart on that site that has the physical properties of various laminates, and so forth.

[runpasthefence]

Awesome, I'll check it out

[A Fn Noob]

If you cant find what you need, there are hard-core geeks at boatdesign.net forums that can give you a layup schedule for your project. They are more about sailboats than speedboats on that site, but very knowledgeable about the fiberglass. It seems this site might take a while to get back up "on plane" after the upgrade.

[Bullzeye]

If you vac an overlay without getting all the air out, you can cause bubbbles to grow. The Ultimate break point of a panel is lowered(weaker) when vaced for the same schedule. The formula is the thickness squared, roughly 10-30% thinner with vacumm so when you change from wet layup to infusion you normally alter the schedule to compensate for the difference.

Always try out your process before the big project.

Here's some info
Good Luck

http://resinservices-reklein.com/contents.htm

http://www.compositeforum.werksberg.com/index.php?

http://www.eng-tips.com/threadminder.cfm?pid=327

http://redrockstore.com/resin.htm

http://www.raka.com/

http://www.epoxyproducts.com/hindsight4u.html#Rotting

Subsribe to this mag, very informative

http://www.acmanet.org/CM/index.cfm

[A Fn Noob]

There's a fellow that's organized! wow

[Bruster]

$5 well spent

http://www.westsystem.info/vabate.html

[A Fn Noob]

Or sift through these results for free:
http://www.google.com/search?num=100&hl=en&lr=&as_qdr=all&q=west-system+resin+filetype%3Apdf (http://www.google.com/search?num=100&hl=en&lr=&as_qdr=all&q=west-system+resin+filetype%3Apdf)

You could change the word resin to other words like composite or laminate, etc. and tweak the results to get what your after. All the west-systems literature is out there floating around on the internet.

[Bullzeye]

A Fn Noob, Thanks

This is definately a process that is hard to learn and teach. The cps of the resin, vac fitting location, how quick the resin sets, how much gassing off of the substrate, are just a few. Any one can kill the project. You need to drop the vac down to about 10 inches or you can pull too much resin out.

For most Peel Ply would be the best all around solution. Cheap and not too complicated. Once pulled, you have a ready to bond to surface.If you grind the surfaces and use PP properly you should be able to get a chemical bond if you stage it right. It will also give you near vaced results as far as fiber/resin ratio.

Resin Research has a 200 min cure that can be thinned with Zylene(up to 5%) for infusion or for penetrating epoxy. Carbon/Kevlar material you want
to overlay needs thin resin to work the air out easily.

PER kicks faster with more catalyst, Zylene causes this resin to kick slower.
More work time on big projects. Probably less gassing off and heat.

Food for thought

RBT Do you have any pics of your infusion project?

[runpasthefence]

Thanks for the humbling information, guys.

I'm thinking this might just be worth the wait. I'm going to to let the pro's handle this.

Thanks again,

Mick

[RBT]

Bullzeye, it isn't really a project. It is a new boat, it is manufactured infused. I cannot post pictures as it is a protected procedure.

RT

[Musashi]

Hi Mick

I'm a boat builder in the UK and use vacuum consolidation all the time on new builds and repairs. Really not a complicated process to do, just need to ensure you lay up the vacuum stack (peel ply etc) correctly and give your self plenty of time to do it. I would normally use only 50% atmospheric pressure and produce the vacuum bag first to test its air tight.

What material is the pad made from? Presealing this with resin will prevent a dry laminate. You shouldn’t use chopped strand matt with epoxy, although the powder bond chopped strand matt is widely used. This is replacing osmosis as my most seen repair.

In terms of laminate schedule, I would use a light woven roving, 165g or 400g are my personal choices as easy to lay up and work with. Bare in mind that fabrics hate 90° corners and will try to lift off meaning a small radius is needed, vacuum consolidating over a sharp corner will result in the laminate thinning requiring extra reinforcement.

Hope you decide to have a go

Tim

[Bullzeye]

RT
I understand you situation an appreciate your input on the board. I've been studying this whole process as a student(hobby) for a couple of years and it is a science in itself. It has co$t me some failed projects too. My hats off to ya and wish I could see your infusion process.

runpas
If you posted some pics of the boat it woud be a lot easier for those that can help to give some direction. You want to be sure of one thing. This is structural and if you delaminate at speed no one can tell you the outcome.
Didn't mean to stop you from what your doing, but be informed.

Personally I like the (RAKA)8 harness S-2 glass with epoxy as it goes around corners and is easy to work with. You don't need CSM with this stuff. If you make a test sample and have CSM in there anywhere, that will be the point of failure when it's pulled.

As far as the CSM goes, you have a P-matt which is the stuff Musashi is using and the styrene can better break down to encapsulate the fiber. The E-matt has an emotion binder thats doesn't breakdown as well. If you calculate the amount of resin needed by material weight you find CSM needs more resin than other materials and adds less strength.

One of the links compares Epoxy/VER and states 2000 psi for epoxy, 500 psi for VER and the other missing number is PER at 300 psi. These numbers depict the resins ability to transfer loads from one layer to the next(in tension and compression) and secondary bond quality.

Musashi
Little things like if you have a contour, you need to add a wrinkle in the bag or it can bridge resin at that point. If a silicone wax was used in the area, even if you rough the surface, nothing will stick to it vaced or wet layup.

The Resin Research epoxy thinned with zylene allows you to use CSM as the zylene will break down the binders as I'm told by Greg Loehr(formulator and owner). This is a UV stable clear surfboard resin. The 200 minute mix was designed for RT to use when you need time to wet out a lot of material. Wake up the next mourning to a cured hull. I'm guessing it takes a couple of days just to cut, layout and bag the hull. around a 20 footer. Infusion is the coolest because you can't form air bubbles when there is no air.

As far as a post cure, you can leave it in the sun and reach the temp needed, around 120 deg. Not a big deal.

Look at these infusion examples

http://www.youtube.com/results?search_query=vacuum%20infusion&search=Search

[Ted Stryker]

That link was pretty cool, never seen it done and wondered what it looked like.. I didn't know if the material was layed up and wet before the bag, or if it was dry assembled and the resin was migrated through with vacuum... I think that the vacuum procedure is what hull builders could only dream about in the past, hard packed laminates with absolutely no excess resin.. I am a blubbering fool for quality hulls, and would just love to have the knowledge and $$ to be able to afford to build My own hull someday as it has been something that I have been completely interested in for 20 years..

[Bullzeye]

Here ya go Ted
http://www.youtube.com/watch?v=s12pUg9ypVU


http://www.youtube.com/watch?v=q_fKlDzemPY

http://www.youtube.com/watch?v=IWiSSLPf6JI



Still cutting edge is spray on vacuum bagging.

http://www.youtube.com/watch?v=V9aX0WcDh7g

Lost foam process in making a fuel tank, some do's and dont's, some other how to's ya'll might find interesting. Carbon battery box, vac'ing a motorcycle fender. I don't care for the look you get when you vac/infuse carbon. It looks flattened too much

http://www.mci.i12.com/carbon/vacuum.htm

[Bullzeye]

The best epoxy is like tar or clay, not something anyone can use easily. Watch closely at the lady applying PrePreg to the mold. This stuff requires elevated temps in the 250* range and then cycled down 1* every 15 minutes or so. As always follow the instructions. The autoclave usually runs in the millions this size because they also use high pressure to hold the material to the mold. Remove, trim and assemble.

If you cool too quick, you create micro crackes in the prepreg. They are using 4X4 twill weave prepreg bc it makes bends fairly well, looks good unpainted and doesn't use a lot of resin as CSM. With blue jeans on, bend your knee and look closely. That is a twill weave, Diagonal lines.

This link is to my favorite supercar, the Zonda F all prepreg, around 33 MPG if you don't visit this site and you better have your teflon coated nonstick underwear!!!:eek:

http://www.youtube.com/watch?v=SOzPQN1fevc

http://www.youtube.com/watch?v=silJgVMSKDc

BTW The spray glue mentioned earlier is Super77, use it sparingly.