Frank and others inspired me to try my hand at flame polishing. Too bad my hand is too burned now to do anything else
The technique of flame polishing takes practice and skill. Since practicing, my skill has gotten worse so I decided to go a different route. I had 10 acrylic signs to make and my time was getting short so found that you can get excellent results with polishing/buffing.
Here are the steps:
Use Cast acrylic and leave paper on as long as possible.
1. When cutting with the laser, make sure the edge lines are as fine as possible with settings. This will save time later.
2. Depending on the the ridges you have on your acrylic, you may be able to skip using low grit sand paper. Start with 220grit dry and sand the edges making sure to use a lighter touch and smooth motions.
3. Change to 400grit wet/dry and make sure acrylic and sand paper is wet and wet often. You will notice the edges look hazy (this is normal). Check to make sure there are no engraving lines by drying the edges with a towel/cloth. Make sure all lines are not visible and the entire area has the hazy look. I didn't notice a big difference going to 600 wet then continuing on the process so you can save yourselve the 600 wet.
4. Depending on the thickness of the acrylic, you can use a buffing wheel or a dremel with a buffing wheel on it.
5. Using a slower speed and buffing compound for acrylic (blue stick). I used Eazypower Plastic compound (model 81031). Move across the edge of the acrylic. Make sure you have enough compound on the wheel.
6. Within a few seconds you should start to see the edge clear up. Make sure the speed of the wheel is slow as to not heat up and cause melting to occur. I used a dremel at 15,000rpm.
7. The difficult part for me about this is knowing how much compound to use and when to change buffing wheels. The dremel ones are cheap so would expect a buffing wheel will work much better.
I found you can use this technique for the surface also. The signs required routing one edge for a slate piece. Once the routing marks were sanded away, the polishing took it to a clear finish that you couldn't tell it was machined.
The first image is just polishing without sanding first. Although the results are not great, for some things it would work fine. The second picture is sanding then polishing.