View Full Version : A question for you acrylic pros...

Kerry Smith II
01-08-2008, 1:52 PM
What is the best way to polish mirrored acrylic without leaving fine scratches?


Scott Shepherd
01-08-2008, 2:01 PM
I shouldn't respond because I'm no "expert", but I can tell you that I have tried the 3 stages of Novus products. The Novus #3 is a heavy scratch remover, then the #2 which is milder, and then the #1 which is Plastic Clean and Shine (also removes the static from it).

Very nice products. You can usually get free sample packets from good plastic distributors as well.

Tim Murphy
01-08-2008, 4:02 PM
were you looking to polish the mirrored finish, or just the acrylic? also is it deep scratches, surface scratches, or haziness? The novus will work good on surface scratches and haziness with towels by hand, but if its deep scratches you will need to buff it out pretty heavily with a wheel of some sort. Buffing anything is an art form in itself so be careful, or even practice on some scrap.
Hope this helps at all! Murph

Kerry Smith II
01-08-2008, 6:48 PM
I have the Novus products and I am using a microfiber antistatic cloth to buff but I still can see tiny hairline scratches when the light hits at certain angles.

Is this something I have to live with?

Scott Shepherd
01-08-2008, 7:19 PM
Unless you flame polish it. In my days as a machinist, I was making some lexan parts and one of the blanks had a bad scratch in it, so I set it aside. The boss came over and asked what the deal was and I showed him the scratch that was already in the blank before I ran it.

He took me and the part back to the welding area and fired up a torch with a small tip on it. He gently feathered the flame over it, time and time again, making sure not to allow the flame to stay still or get it too hot. All of the sudden, the deep scratch completely vanished like magic. It was one of the best tips I had in my tool of tricks for years.

I used to demo the technique by taking a car key and scratching it pretty good (or bad) and then I'd work it completely out.

People on here mention flame polishing from time to time, and I assume it's the same technique. It's a bit of an art to it and you can quickly and easily put too much heat and it'll blister and then it really is scrap.

Not sure what others use to do it, and back then, it was always an oxy/act. torch with a super small tip.

Bill Cunningham
01-08-2008, 11:35 PM
Butane is probably closer to the correct temperature.. I have always had a much better job using butane than any other gas.. I have this neat little torch that is powered by a Bic lighter.. You just drop it inside, (it has a pezio electric button) and the torch uses the lighter as a fuel source.. Just like the bigger Ronson torches, the flame seems to be just the right temperature..

Vaughan Raymond
01-09-2008, 3:10 PM
Acrylic is best polished with a hydrogen/oxygen flame. Be aware that machining or heating acrylic puts internal stresses in the material. If you then try to use a solvent glue such as methylene chloride, it will craze and even shatter. In the aircraft world where we form acrylic often, we put it though an anealing oven after any machining or heating. If it is a small enough item, you could aneal it in your oven but make sure things are well ventilated. I can't remember the time and temperature off the top of my head but if you want to do it, pm me and I'll look it up.

Bill Cunningham
01-10-2008, 10:21 PM
Never thought about using hydrogen/O2 for plexi! It burns about 700 degC. hotter than butane, only methane burns cooler. I always figured the cooler the flame, the better it cleared the plexi.. Used to use Hydrogen years ago in a U/W cutting torches, but that gave way to U/W OxyArc which could be used much deeper, faster, and safer.. When the Hydrogen/02 torch snapped out u/w it was like a gunshot to the ears..:D

Ken Garlock
01-11-2008, 12:42 PM
Hi Kerry. Back in the dark ages when I took an eighth grade shop class, the teacher had us sand the rough surfaces to get the band-saw marks out, and then work on it with 4-O steel wool until we had an even dull surface with no visible scratches other than what the wool left.

The final step was to take the item over to the buffer loaded with red rouge and buff the item to a clear surface. If you had done your sanding properly, it didn't take a lot of buffing. Of course there were those that would shortcut the process and all but burned out the scratches on the buffer.