Polishing Acrylic Guide, Tips, & Tricks.

A guide of sorts. This isn't the 5 minute process you might have seen elsewhere. This version is to get glass like clarity. It doesn't matter if you are polishing a frosted block or an already clear block the instructions are the same. The clear blocks will still have machine marks that need to be removed. I'll be using an EK CSQ D5 top that is frosted stock.


In this pic you see the machine marks that we need to get rid of. For the CSQ blocks they are on the inside only. They must be removed to have glass like clarity at the polishing stage.



First you use a heat gun on the EK badge. Get it nice and hot but don't melt the acrylic . If you are not going to reinstall the EK badge you will need to sand the recessed circle at each stage.


Start w/ 400g on the bottom of the block. Use a piece of glass to make sure you are sanding flat when you are doing the bottom. You don't want an uneven sand job and possibly get a leak. For the flat part of the bottom you will want to sand in two different directions. You don't need a lot of 400g. You will also need to use 400g on the inside machined areas where the coolant flows.


Then move up to 800g. You can do the tops and side w/ this grit as well. Not too much pressure on the top though as you want to maintain the circles and print. By the end of 800g all tool marks should be gone. Once again sand in the coolant channels. Make sure to get the edges.




Move up to 1000g. Do the entire block just like above.



Rinse and repeat w/ 1500g (if possible) and 2000g. Should look similar to this at the end of 2000g.



Now the polish. Use a good acrylic / plastic polish. Not a metal polish. It will cut polishing time significantly. I use Meguiar's PlastX. You'll need some good polishing cloths too. Old t-shirts work.




Now go to town on the polishing. Use a liberal amount. Continue polishing w/ one part of the cloth until the majority of the polish has been taken off the acrylic. Then move to a clean part of the cloth and continue polishing until perfectly clear. You shouldn't be able to see any scratches of any sorts as long as you sanded properly. You can easily do a second run w/ the polish as it takes very little time.

To polish inside the CSQ circles take a toothpick. Break off the sharp end. Then stick it in to a double folded cloth. Use the end of the toothpick w/ some polish to get the insides of the circles as much as possible. To clean insides the threads you can corkscrew in a cloth covered in polish. Then repeat w/ a clean part of the cloth.


Finished product. Notice how the inside of the block reflects light. A block that has not had the insides sanded and polish look dull. This will also make non-pastel coolants really pop.










Edited by lowfat - 4/21/14 at 5:55pm

About 3.5 hours total of sanding and polishing I'd wager.

Although I have never done a bridge larger than a single. I do believe the larger ones are more difficult since you can't sand inside the coolant channels.

As for coming stock like this. Not going to happen. Even the clear blocks they sell will have machining marks. It really isn't possible for the CNCs to make cleaner cuts. Hand polishing is pretty nessessary if you want really clear acrylic.