Contact   Imprint   Advertising   Guidelines

Fibreglass won't stick

Here you can exchange your experience and datas about your home build boards
andy666
Rare Poster
Posts: 8
Joined: Sun Sep 11, 2016 2:29 am
Local Beach: Brighton, QLD, Australia
Favorite Beaches: Evans Head, NSW, Australia
Yeppoon, QLD, Australia
Style: Free ride, buggy
Gear: Flysurfer
Brand Affiliation: None
Has thanked: 1 time
Been thanked: 0

Fibreglass won't stick

Postby andy666 » Sun Sep 11, 2016 12:41 pm

Im hoping to build my first board, a big light wind twin tip. The plan is to laminate together 2 sheets of 4mm plywood and then fibreglass the top and bottom. But so far things aren't going well.
Did my first test run yesterday and it was a failure. (I'm using west system epoxy resin with 206 slow hardener and 300gm fibreglass)

I just tested on a small section of timber, with some paddle pop sticks on it, to see how well the fibreglass would stick and form to shape. I also wanted to test my cheap vacuum system, which is just a hose attached to the deflate port on my kite pump.

well the entire thing was a failure :(

the kite pump pulled a good vacuum down to about -0.8 bar, but I couldn't get the bag to seal so it would hold vacuum for more then about 20 seconds.

then when I unwrapped it this morning I was not happy with the fibreglass. It didn't form well around the paddle pop sticks (this could be due to the vac failure), and it didn't stick to the timber very well. It looked good to start with but when I gave it a flex test the fibreglass started to unstick (you can see in the pictures where it has unstuck and turned white). I then just grabbed an edge and it peeled easily off the timber. I know some people only put their fibreglass to the edge and not around, so there must be a way to make it stick?

What am I doing wrong?

I messured the resin using a digital kitchen scale, so I know the mix ratio was right. I wet the timber first, lay the fibreglass on top and then finished wetting out the fibreglass until it was clear.
did I absorb too much resin out when I vac bagged it? I just used peel ply and a breather layer over the fibreglass.
do I need another layer of resin on top of what is there to so help seal it better? But doesn't that defeat the point of vac bagging?

Please help

Also, should I cut the fibreglass cloth to size before laying it on, or leave it hang over the edge and trim the excess once the resin has dried.

Image

Image

cosmo
Medium Poster
Posts: 153
Joined: Sun Jun 24, 2007 11:17 pm
Has thanked: 0
Been thanked: 0

Re: Fibreglass won't stick

Postby cosmo » Sun Sep 11, 2016 1:55 pm

You need to vacuum it full time, not only 20 seconds or one hour. How it's possible not to seal such a small bag? Get a electric pump and a roll of sealing tape.

TomW
Very Frequent Poster
Posts: 3585
Joined: Wed Oct 05, 2005 6:43 pm
Kiting since: 2001
Local Beach: Vejbystrand, Lomma
Gear: TW Surfboards hydrofoil board 110
Gong Veloce M, 100cm carbon mast
Ozone Hyperlink V1 7m
Hyperlink V2 9m, 13m
Concept Air Wave 4,5m
Brand Affiliation: None
Location: Sweden
Has thanked: 53 times
Been thanked: 193 times

Re: Fibreglass won't stick

Postby TomW » Sun Sep 11, 2016 3:41 pm

Ok. There's a lot of potential problems.
1. You have to pre seal wood with epoxy
2. Popsicle sticks and ply may have a coating or contamination. Sand everything first, clean off dust and clean with Denatured alcohol, and preseal with epoxy
3. You have to work glass into depression, so there is sufficient glass to fill space. you have glass tenting.
4. Bag is tenting. Need flexible bag
5. You need a release film( any old plastic film) and breather felt. Old fleece works. Peelply not necessary and can suck a lot of resin.
6. Your bag has to seal and hold vacuum.

You are doing it right to experiment. Fail small, keep lab notes of procedures and Materials. Expect to get it wrong a few times. You'll figure it out.

User avatar
downunder
Very Frequent Poster
Posts: 2811
Joined: Mon Jul 01, 2013 7:16 am
Gear: building my own
Brand Affiliation: None
Location: Perth, Australia
Has thanked: 153 times
Been thanked: 160 times

Re: Fibreglass won't stick

Postby downunder » Mon Sep 12, 2016 2:59 am

TomW

#5, nope, not *any* plastic. By all means use the proper perforated 'bleeder' film for the vac applications. It's reusable btw. If using *any* plastic, the epoxy might dissolve it and ruin the project.
#6, the vac bag can seal but it's never going to hold for 10 hours or more. That would be really, really good vac bag :) The trick is to top up the vac from time to time, duno, every few mins? Secs? Hours? Depends on a seal :)

The FG is dry because of : "I just used peel ply and a breather layer over the fibreglass." - this sucked everything. FG is not conforming to 90 degrees bridging, you'll need to sand this tiny edges to at least 45 degrees angle.

Remember, we are using a vac not because is needed for a FG, but because we making a rocker and concave by bending sheets of material. If the board is already rockered and shaped, you could glass it with a hand layup. Like the surfboards are. No vac.

D.

PS
I would stay clear from a ply wood even a marine type. How would one know of any voids below the veneer? There are many, trust me.

plummet
Very Frequent Poster
Posts: 6819
Joined: Sat Aug 29, 2009 11:25 pm
Local Beach: EE
Favorite Beaches: NZ
Style: Terrain riding
Gear: Old wornout ozone.
Plummet hydrofoil and mutant
Brand Affiliation: None
Has thanked: 11 times
Been thanked: 224 times

Re: Fibreglass won't stick

Postby plummet » Mon Sep 12, 2016 4:10 am

To add to the above.

Expect that your vac bag will leak!. its almost impossible to get a perfect seal. Look into making a fridge pump style vac pump system. See my attached picture.

Did you allow enough time to cure before the peel test? wait at least 24hrs even then you are not a full strength.

As Tom states check in the wood by sanding it. If its a particularly oily wood then rub it down with acetone 30 mins prior to lay up. I have never pre-sealed the wood first.

PS I'm using west system with 206 hardener.
Attachments
10446696_664461880294859_492350605125982661_n.jpg

andy666
Rare Poster
Posts: 8
Joined: Sun Sep 11, 2016 2:29 am
Local Beach: Brighton, QLD, Australia
Favorite Beaches: Evans Head, NSW, Australia
Yeppoon, QLD, Australia
Style: Free ride, buggy
Gear: Flysurfer
Brand Affiliation: None
Has thanked: 1 time
Been thanked: 0

Re: Fibreglass won't stick

Postby andy666 » Mon Sep 12, 2016 4:39 am

Cheers for the tips.
I didn't think about cleaning the timber with acetone, so that didn't help things.
I only waited about 18hrs before doing the "peel test", so I might check it again tonight and see what it's like.
Hmm, I guess the big decision now is either build a vac pump or fibreglass by hand...

User avatar
downunder
Very Frequent Poster
Posts: 2811
Joined: Mon Jul 01, 2013 7:16 am
Gear: building my own
Brand Affiliation: None
Location: Perth, Australia
Has thanked: 153 times
Been thanked: 160 times

Re: Fibreglass won't stick

Postby downunder » Mon Sep 12, 2016 5:07 am

andy666 wrote:.
.

do I need another layer of resin on top of what is there to so help seal it better? But doesn't that defeat the point of vac bagging?
.
.
Yes and no.

The point of vac bagging is not to give you the finished product.
After you take your work out of a bag, you'll need to apply a few new coats over the FG. Plus varnish.

If you do not do that, the sand will eat a FG in no time :) Particularly under the foot pads. I just did the maintenance on my board after a long time (will open a new thread soon). All FG exposed under. For the boards that I'm selling, 3-4 layers of epoxy and 5 layers of varnish is not unusual.

To get the mirror shine (varnish, not epoxy), takes a lot of elbow grease. If not varnished, epoxy will degrade, some faster, some slower, no matter what. This is the reason why me PU rails are still crisp in color and epoxy faded long time ago.

Also, you'll need SS footpads inserts, don't remember if you got those from me...

D.

User avatar
rynhardt
Very Frequent Poster
Posts: 977
Joined: Wed Sep 11, 2013 3:51 pm
Local Beach: Langebaan
Favorite Beaches: Langebaan
Style: Freeride
Gear: Cloud C2 17
Hoff Twinwave
Brand Affiliation: None
Location: Johannesburg, South Africa
Has thanked: 24 times
Been thanked: 29 times

Re: Fibreglass won't stick

Postby rynhardt » Mon Sep 12, 2016 10:37 am

downunder wrote: Yes and no.

The point of vac bagging is not to give you the finished product.
After you take your work out of a bag, you'll need to apply a few new coats over the FG. Plus varnish.

If you do not do that, the sand will eat a FG in no time :) Particularly under the foot pads. I just did the maintenance on my board after a long time (will open a new thread soon). All FG exposed under. For the boards that I'm selling, 3-4 layers of epoxy and 5 layers of varnish is not unusual.

To get the mirror shine (varnish, not epoxy), takes a lot of elbow grease. If not varnished, epoxy will degrade, some faster, some slower, no matter what. This is the reason why me PU rails are still crisp in color and epoxy faded long time ago.

Also, you'll need SS footpads inserts, don't remember if you got those from me...

D.

I have to disagree with you a bit here. You can get a finished product out of the bag, provided you have the right system.

andy666
Rare Poster
Posts: 8
Joined: Sun Sep 11, 2016 2:29 am
Local Beach: Brighton, QLD, Australia
Favorite Beaches: Evans Head, NSW, Australia
Yeppoon, QLD, Australia
Style: Free ride, buggy
Gear: Flysurfer
Brand Affiliation: None
Has thanked: 1 time
Been thanked: 0

Re: Fibreglass won't stick

Postby andy666 » Mon Sep 12, 2016 11:19 am

I was just going to use epoxy enamel paint (kill rust) over the fibreglass to protect from UV light. Hopefully that will work?

Yeah, I already got the stainless inserts from eBay.

plummet
Very Frequent Poster
Posts: 6819
Joined: Sat Aug 29, 2009 11:25 pm
Local Beach: EE
Favorite Beaches: NZ
Style: Terrain riding
Gear: Old wornout ozone.
Plummet hydrofoil and mutant
Brand Affiliation: None
Has thanked: 11 times
Been thanked: 224 times

Re: Fibreglass won't stick

Postby plummet » Mon Sep 12, 2016 11:51 am

I don't use any uv stabilised paints on my boards. I have had no epoxy failure in 16 years of making glass and carbon boards. So.... I don't think you need that product. My last 3 boards I didn't add any additional layers of resin either. But I don't need a mirror finish either.


Return to “Gear Builders”

Who is online

Users browsing this forum: No registered users and 55 guests