Thursday, November 23, 2017

Going Even Bigger

Binks Mach 1 PCX with Pressure Regulator
Now that we have proved the concept of spraying Externally Catalyzed Duratec Additive mixed with ISO/NPG Gelcoat using a Binks Mach 1 PCX spray gun, the time has come to go big.

The New Air Compressor
I was renting an air compressor from Joe, one of the painters in the boatyard.  It worked out well for the cockpit locker lids but did take a while to pump back up to pressure and couldn't keep up with continuous spraying.  It was costing $4/day and there were many days when it just sat while we were prepping, or sanding, or whatever.  I found a larger compressor online for $400 delivered, so I bought it.  It should pay for itself by the time the job is done and I'll be able to sell it to recoup some of the cost.

Spraying Gelcoat like Paint
Starting small has been our mantra all along and even though the confidence factor is good, we still expect that we will encounter unknown factors.  Repeatability is the key to this project.  The area above the transom rub rail seemed like a good place to start.

Sprayed Transom and Hulls
Catalyst Pressure - 2.6 psi
We set up to spray and used the new compressor.  Since it seemed like all the bugs had already been worked out, we started spraying.  Big mistake.  The cutoff pressure of the new compressor is 120 psi whereas the rented one was 100 psi.  This changed the pressure pot pressures which were checked during initial compressor run but not at full pressure.  This made the gelcoat pressure 5 vs. 6 psi.  The gelcoat was way over-catalyzed and in this case, refused to harden, even after 24 hours.  So, we had to scrape and sand all the gelcoat off of the transom.  2 days wasted.  Live and learn.  Always spray a test pattern on something other than the boat and wait for it to kick, then spray a small area of the boat checking both test area for proper catalyzation.  It is time consuming and may kill and hour but it is well worth it and a good lesson learned.
Gelcoat Pressure - 6 psi

Here are some photos of the transom sections that were sprayed with gelcoat and guide coat.
Partial Application of Guide Coat

Fully Guide Coated

Starting to Sand off Guide Coat

Sanded a small test area with 120/330/800 grit then Compound

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