We’re back again with getting the hull ready for detailing. Everything you see here was pretty much learned by following Brian Stark’s procedures on his various projects, with trying to get a flawless finish on the plug mould. Really though, for this application there is no one better type of person to follow than a professional body man, of which he is
Number one, using very heavy grit sandpaper I’ve sanded down the entire surface of the plug, and this includes all the details. All the scribed details have been filled. Yes, I am redoing all the details as I feel I can do a better job than on the Permit. Block sanding is the order of the day to smoothen out the high spots. To smoke out the low spots, I spray some cheap black paint on in a mist coat and then block sand when dry. If done correctly the low spots should show nicely when done, and then fill them up with an appropriate filler and sand. I kept repeating the process until I was happy.
So, with all the things filled that needed filling like details and imperfections in the surface I proceeded to block sand the whole thing down. I am not worried about filling deep scratch marks this time however, I have a secret weapon (of which I’m about to share with all of you) that will eliminate these. Let me first illiterate my goal here, I need a decent surface in which to scribe to and later sand to a polish. The Permit has an MDF substrate (among other different fillers with different hardnesses beneath what I would call a pretty thin layer of Acrylic auto body surface primer. Don’t get me wrong, that primer is the very best for finding flaws and its extreme sandability, but in that case it was the wrong tool for the job. It can be polished but the layer won’t be thick, and when the layer isn’t thick you will be scribing into MDF (or whatever else is underneath that has a different hardness) The scribe lines will also collapse if too close to other scribe lines because the primer just doesn’t have the structural integrity that is needed. This caused massive amounts of spot repairs, and frankly the scribes just weren’t that clean.
So here is the answer to all that. After much research (actually I landed on this stuff by fluke) I found some primer that is made exclusively for fiberglass plug mould finishing. I was actually was pursuing the polyester version of this stuff, but the guy at the store convinced me that this vinyl ester stuff was better. It can be sprayed on to almost 1/8” thick in one spraying
Now, even though this is super hard, self leveling, and nice to scribe into, this stuff is very thick and has to be thinned quite a bit with styrene to be able to spray out of my conventional HVLP gun. It also has a 10 minute pot life after being catalyzed with MEKP. Oh Ya, did I mention that this stuff stinks?? The smell somehow got into my house from my attached garage, even with all the doors shut and all windows closed on the house. Definitely use proper breathing filtration of even supplied air and a mask when using this, no question asked!
This also isn’t as easy to sand. I started my polishing procedure using 220 grit wet sand, then going to 340 and then stopping for now at 400. The things to remember are to change your water after going up to the next grit paper and squirt in a little dish soap in each batch. This prevents clogging in the sandpaper.