Dry spot and air bubbles

Just finished the lam of the bottom of my semi-gun thruster. I used UV resin and it made a HUGE difference to the final outcome. Even the rails came out pretty good. I did, however, make a couple of boo-boos. There is one dry spot and a couple of bubbles that are obviously raised above the foam. How do I address these problems? Do I try and add more lam to saturate the dry spot or just leave for the deck lam to cover? With the air bubbles do I try to cut them out and patch or do I inject them with lam resin? Any help appreciated

Ado

You have to get rid of the bubbles and put a patch down. Injecting resin is not a good idea, as there will be no bond between the cloth and foam, and no structural strength… plus, you’ll have a big bump there forever.

I like to fill in the dry spots before I lam over top of them, just in case anything goes wrong - you can fix it before you… well…can’t.

Once UV resin, always UV resin.

The dry spot, see if you can wet it with resin, if the fibers are exposed. Usually (as in my case) there is a batch of hard resin covering the dry spot. I had to sand into the weave, sand it out, then repatch.

On one repair I got lucky i was able to chip the dry resin away after sanding it, exposing the dry cloth and a simple re-wet fixed it.

Bubbles, gotta thank the Genius for this first trick. two ways.

  1. slice the fabric open on one side of the bubble. You can pierce a needle hole, but the slice is better, allows more stuff to move in and out. I used masking tape to build a dam (4 sided ) around the open slice. I filled the dam up with resin. Using a small dowel, I gently pumped the bubble, kind of using a billows type of movement. Eventually the air inside was replaced with resin. I cleaned out excess resin from dam, removed the dam, cleaned some more (be sure not to disturb the bubble or else it may suck in some air and put air bubbles inside of it).

I got a another short dowl, waxed it down (paraffin original sex wax). I got a weight (rock / dirt clod inside of a ziplock bag). I put the short dowl on the bubble (it was as thick as a US quarter), slowly pressed it down, put the weight on top. Cleaned excess resin running out. This compresses the bubble down and I let it kick n cure. Then I pulled the dowl and weight off.

Mainly for smaller jobs. If you’d use this for a large delam, I suppose you could slice holes in multiple sections and get resin inside, then cover it all in wax paper and use plastic covered sandbags to hold everything down.

  1. you can use a dremel (also used in #1 dremels are useful), to slice open and cut out the bubble, and repatch.

I went with #1 because the bubble had captured one of the logos for my board. If I would have cut the bubble, half of my logo would have went with it. Otherwise #2 sometimes is easier esp if you have a large delam.

I used RR epoxy during this op.

Thanks Vmuch Hiro.

Did that and they turned out sweet. Now just battling the old fold glass around the nose dilemma. Dont you love how the glass unravels at the extremeties of the board. Patches will sort this out i think.

Thanks again.

Ado