In preparation for the canoe build project I have been tinkering around with fiberglass for the past week and a half. My first little project is a new ash tray for the S10. Since I do not smoke I decided I could make a tray that would effectively hold my cell phone instead of cigarets.

Ash tray with first layer of fiberglass

This first project allowed me to toy around with molds. I started by putting a layer of fiberglass over the original ash tray which slides into a cavity in my truck. This was my first “challenge” as I wanted to use the ash tray as a mold and would need to remove the new tray from the mold without destroying both. After consulting a few websites I learned that vegetable oil, vaseline, WD-40, or any petroleum based lubricant *should* work. I went for WD-40 and it did not “work” in the sense that my original ash tray was able to be removed without any breakage. The epoxy ended up bonding in a couple of spots plus I think the shape of the ash tray created a few places that just naturally resisted the whole “lifting out” concept. I also felt when laying the fiberglass that cutting a bunch of pieces would “weaken” my structure so I just use a couple of large pieces of fiberglass and folded as necessary. This was not a great idea as it created many air bubbles in the finish and helped create the not releasing from the mold situation.

First phone tray "mold" complete & broken original ash tray

I did seperate the mold and the new tray fairly successfully, although I would not recommend WD-40. The new tray I created looked pretty good with some trimming and sanding. But of course it was too big as it was created by layering the outside of the ash tray. So to create a sized to fit tray I created a second tray. This time I used the new tray as the mold, and laid the fiberglass in the new mold. Again a mold release agent was needed. Having seen the WD-40 not work I decided a nice bearing grease would be a great idea. I also decided it would be a great idea to actually pre-cut pieces of fiberglass to fit the shape of the mold. I also omitted fiberglassing the “ridge” in the middle of the ash tray as that is what I am primarily looking to get out of the way with my new phone tray.

Phone tray mold greased up & pre-cut fiberglass for the first layer of the phone tray

This second tactic of cutting precise shapes of fiberglass worked very well. The grease as a mold release agent was so-so. It did help the new part release from the mold, but it was a HUGE mess to work with and left the finish part with a red tint from the grease I used. After some trimming and sanding the new phone tray fit into the cavity quite well. My next steps are to layer the inside with a second layer of fiberglass to strengthen the lltray and to build out the final internal shape to support my phone. Once that is done a little sanding, a touch of paint, and it will be ready to go.

Key Learnings

1. Cut your fiberglass into pieces to fit your mold. Laying a bigger piece over the mold and folding or creasing does not work well at all.
2. Do not use WD-40 or grease as a mold release agent. WD-40 does not work well, and the grease makes a huge mess and bonds into the dried fiberglass.