Introduction: Build a Surfboard Episode 3: Laminating and Vacuum Bagging

By www.mit.edu/people/robot
About: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of www.zcorp.com, manufacturers of "3D Printer" output devices. His detailed drawings of traditional Pacific I…

Learn to make a surfboard from the famous Johnny "V" Voxlund in Haiku Maui.
Continues the saga begun at
Build a Surfboard and
Episode 2: Sanding

Johnny invited me over to explain his bagging setup and watch him pull the board out of the bag. It was too hectic for spectators when he bagged the board due to a severe windstorm.

There's a lot going on in this photo.
He used UV cure resin so he had to make it dark.
He set up a tarp tent over the front of his shop to keep out sunlight. High winds made the tarp flap, making work very stressful. If the tarp blew away the board would be ruined by sunlight in mere seconds.

Step 1: All in the Bag

This board has a woven bamboo flame job on the deck.
It's structural as well as decorative. It makes the deck stiffer and prevents heel dings in the deck.
At the moment the vacuum is still sucking air out of the bag around the board. That compresses the whole board and clamps the bamboo matting down tight.

How did it all get in there?

Before putting the board Johnny worked on it outside in the dark tent.
He catalyzed some normal polyester resin and spread it on the underside of the bamboo matting. Now the clock starts ticking. That resin will set up in 1 hour.
Then he laid the glass over the top of that and squeegeed in the UV cure resin.
Now the board is vulnerable to sunlight.

Step 2: Into the Bag Without Touching the Bag

Johnny says: "No one else does it this way. Everyone else tapes down the glass all around so it won't shift when they slide it into the bag. I hate doing that. So I figured out how to put it in the bag without touching the bag."

The secret is the fan over his left shoulder. He sets up the bag hanging from hooks, tape, and wire from the ceiling. The bag's mouth is open facing the fan. When he turns on the fan it blows air into the bag's open mouth, fully inflating and holding the whole bag open so he can put the board inside without touching it. Then he turns off the fan and the bag deflates, the top falling gently down onto the board.

Step 3: Vacuum Pump

He says "This is a really good pump. You can let it run all day".
The manifold with multiple valves is there to run vacuum hoses to multiple boards.
The vacuum guage lets you check to see how good a vacuum you're pulling.

Step 4: Carpet on Hose End

There's a piece of carpeting folded around the end of the vacuum hose where it goes into the bag.
That spreads the airflow around and keeps the bag getting sucked into the hose, plugging it.
He says "You can put the carpeting over the whole board if you want, as long as you don't glue it to the board."

Step 5: Wetting Out the Glass

When you put the resin on the glass it's important to get just the right amount.
The wrinkles you see here are not a problem. As long as the glass lays flat it's easy to sand off ridges of resin.

Johnny only put resin on the area around the bamboo. He's pointing to the dry area of the cloth. The rest of the cloth is left dry. He'll put resin on that in a separate operation. Fully wet or fully dry is okay. The problem comes when a layup is "starved".

If the layup is "starved" there will be areas of cloth not fully saturated with resin. The second photo shows a small area like this. If the layup is starved you'll see the diamond pattern of the cloth weave. The solution is to push resin in and bubbles out with a squeegee.

Step 6: Pushing Bubbles Around

The reason he used the UV cure resin is to have unlimited time to work out the bubbles.
It's hard to see in the photo, but here's a small bubble he missed under the glass.

He describes a harrowing incident. A big gust of wind starts to blow the tarp away that is protecting the board from sunlight. He throws himself in front of the board with his arms out to shade it.
"One spot got the sunlight on it, and it got hard just like that!" He snaps his fingers. But that spot was okay already. Good thing I saw it happening and jumped when I did, or this spot over here would have been all bubbles." He waited like that, shading the board, until the tarp flapped back. Then he fixed it and went back to pushing bubbles out of the layup.

Step 7: Removing the Bandages

He disconnects the vacuum hose and peels off the tape holding the end of the bag closed.
He gently peels the bag off the board. It looks like a plastic bag, but it's a tough, slightly elastic urethane rubber that can be used many times.

The Fiberglass Hawaii store in Kahului sells these bags locally.