Saturday, December 16, 2006

Bubbles!

No, not that one. Having saturated the glass with epoxy on the final seam between the hull and deck and monitored it for a period to ensure that no dry spots or bubbles developed, I left the seam to cure on it's own. As soon as I turned my back a bubble developed, lifting the glass cloth and forming a pocket about 1 3/4" long. Once the epoxy had partially cured I excised the cloth over the bubble, trimming away any loose glass. In the photo below you can see the piece of glass/epoxy which has been cut out

I then scraped the edges in order to allow a smooth transition.

Later, while adding a final fill-coat of epoxy to the hull, I epoxied a patch of glass in place. This time I baby sat it for a few hours in order to prevent the repeat of the bubble. The bubble did come back (the air seems to have been coming from the slight gap that is the seam between hull and deck) but at least I was able to minimize it by pushing out the air as it accumulated. In the end I had to be satisfied with a small bubble in the glass which was largely filled with a subsequent application of epoxy.

With the seam taken care of, I rolled on a final coat of epoxy onto the entire boat to completely fill the weave of the cloth and add a layer of protection for the underlying cloth. With the shop temperature stable at about 20C, I used a West Systems foam roller cover* which I cut in half and used on a small paint roller handle. After mixing the epoxy in small batches I poured it into a paint tray with a small disposable insert which has the added benefit of allowing heat from the exothermic curing epoxy to dissipate better than when it is pool into a mixing container. I started in the morning by rolling a coat of epoxy onto the hull. The foam roller applied the epoxy in a nice thin layer, but left a million tiny bubbles behind (it made little difference how much pressure I applied nor how much epoxy was loaded on the roller, and the epoxy was warm). Thus, I tipped off the epoxy coat as described on the West System web site. The strategy I used was to roll out a section of epoxy on the hull running the roller perpendicular to the boat, doing about 3 feet on one side, then going to the other side and doing another 3 foot section, reloading the roller as necessary. I would then go back over both with a dry foam brush and brush the epoxy parallel to the boat then start the process again on the next section. Once the coat was complete, this was allowed to cure for about 10 hours until late in the evening I repeated the process on the deck. Both coats overlapped at the seam so that the seams received two fill coats of epoxy. The boat now looks pretty good again with that nice wet look of fresh epoxy. At some point I will have to ruin it all by wet-sanding the whole thing to smooth out all the little bumps (the epoxy does not give a very smooth finish in my hands) and prepare it for the varnishing.

Here is what that bubble looked like after the repair and a fill coat of epoxy:

I may have to add another fill coat to this area, but otherwise it should be barely visible by the time everything gets smoothed out and eventually varnished.

I also set my daughter into the kayak so that she could try it out and to pose for a couple of photos.




*I picked up a couple of WS roller covers at a local woodworking store which was having a closing out sale in June. I took the opportunity to purchase on sale some of the "800" polyurethane foam roller covers, a couple of the "804" mixing sticks, and a couple of the "808" plastic spreaders (squeegees). A couple of weeks later the rest of the inventory was auctioned. I had hoped to be able to pick up a number of items for a low price, including a dust collector, bench sander, etc. but everything went for way more than I could afford. I was getting rather annoyed at the fellow who kept bidding on everything I wanted and obviously had more money than me to spend (which isn't saying much, I was really only willing to spend a small amount of cash). I found out later that this fellow was starting a woodworking shop for inner city youth which produces custom furniture for sale. It seems the tools were being purchased for a very good cause. Everything I chose to bid on I was quickly outbid by others in the room. In fact, I usually didn't even get into the bidding before the price went beyond my limit (I believe some of the items went for more than retail price!). The one area where there was very limited interest was in the inventory of fiberglass related items. They had a couple of gallons of WS epoxy and hardener but this too went for more than I was willing to pay (I didn't really need more epoxy after all), but there was a roll of 6 ounce glass cloth on a large stand that I think only one other person bid on and they were not very enthusiastic about it. Thus, I was able to purchase about 10 yards of West Systems brand 6 oz cloth for $30. Now of course I'll have to build another boat in order to have a reason for using it.