The Vegatable Oil Insight

Last night, just after I got in bed, my mind was still racing with my "Craze and Haze" problem.  As I mentioned in my last post, the problem is that I should expect the inside of the panels to wear down over time.  Extruded acrylic (rather then cast) has a lower molecular weight and consequently is more prone to "crazing".  Crazing is basically a bunch of really tiny cracks and makes the panels look white, since the light becomes scattered.  Beyond this, the particle panels concept requires a particle slurry made out of abrasive micro-particles constantly wearing at the inside of the panel.  This, more then anything else, is going to cause scratching. 

My first thought about this problem is that the water would fill the scratches, and since water has a high(er) index of refraction, it should lessen the effect.  I tested this last night, and the results were not quite as good as I wanted.  I took a piece of left over acrylic I had lying around and I roughed it up really good with sandpaper.  I then sprayed some water on the surface.  To my credit, it does make a difference, as you can see below, but it still leaved something to be desired.

Just the piece of acrylic with half of it sanded to simulate heavy crazing:

Now I sprayed water on the surface. You can see it helps a little.

 My insight last night was that acrylic is hydrophobic.  I think that the water is not filling the cracks because of its surface tension.  So rather then water I smeared a little vegetable oil on the surface.  As you can see, the totally scratched surface is completely repaired.  I left a little bit of the edge of the acrylic piece without oil so you can see that this is not just another piece.

So here is my crazy idea.  What if I put some vegetable oil (or some other oil) in the recirculation tank and pulled water from the surface of the tank?  Since oil floats, this would cause the oil to be pumped up to the panels first.  I have designed a particle by-pass system (I still need to blog about that), which should cause the oil to bypass the particles and sit on top.  (I have a hard time imagining the oil pushing through the particles, but perhaps that is not a problem)  When the water arrives, it pushes the oil up the panel and out the top, coating the inside surface.  Since both the oil and the panels are hydrophobic, I should end up with oil sticking to the inside of the panel.  This should have the effect of (1) protecting the panel and (2) filling in any scratches or damage that develop.  At night, the panels are drained back and the process starts over again.  In essence, the circulating fluid contains a "repair and protect" agent. 

Well, that's the idea.

I have over spent my time budget on particle panels and its time to get back to my other work.  It may be awhile before my next post, as I plan on building a new particle panel design and I just ordered the materials.