blake_l
Member
Hi, all. Just thought I'd post my experience so far with plexi finishing. I think I'm finally starting to get something decent.
After doing plenty of reading around here, I mixed up my first batch (which has now become my starter). I tried applying it straight from the can - it was super thick, but gave a _great_ depth right away! Bad thing was, it was too thick and dried too fast - it was a lumpy / ridgy mess, and even de-laminated from the pen when I tried to sand it off! But I could see the promise in it, so I tried again. I got a small plastic bottle with a narrow applicator tip from Rockler (which thankfully has not dissolved in the Acetone - see note below) and used that to mix my application mix. I went quite a bit thinner - more like think CA. It seemed to work OK... sometimes. Worked great on long flat surfaces (think B2B pens), but any time I had any kind of tight curves, I lost the finish in that area during sanding. Took me a while to put it together that that is where it was occurring - I just kept noticing that I didn't have a good finish after I finish sanded. I don't know if there's another way around that. At some point, I always noticed something wrong, and sure enough, there would be a few spots with no finish left. Anyway, I tried applying more finish in the problem areas and _lightly_ sanding - it worked, but took forever. I finally decided to try a new mixture - I went about the consistency of medium CA this time, and I think it's working _lots_ better!
For those interested, here's my procedure:
1.) Sand through 4000 MM.
2.) Slow lathe down - I have a Jet midi and go the next-to-slowest speed, which I believe is about 800.
3.) Using a folded over paper towel (I like to get a long, narrow strip as it takes many light applications), apply a couple of drops of the mixture and wipe on from one direction.
4.) More drops, wiping on from the other direction.
5.) Apply ~10-15 coats.
6.) Start sanding again with MMM 2400 or 3600 - depends how many "ridges" you have. It takes a bit of getting used to it, but I have reduced the ridge height and been able to start with 3600 or 4000 sometimes. (ridges are relative - it should be pretty smooth when you're done applying plexi)
7.) It does sometimes help to sand lengthwise at the lower grits
8.) Sand through 12000.
9.) Maguire's swirl remover
Random tips:
- Don't use vinyl gloves! Acetone is also a solvent for vinyl, apparently!
- Experiment with the mixture viscosity - too thin and you won't leave behind enough plexi. Too thick and it turns into a mess. Unfortunately, I don't have anything more concrete than that.
- Quickly wipe on the finish and _leave_it_alone! Can't stress this enough - one time, you'll think that you can use the acetone to smooth out the surface without having to sand as much (at least I did!) - if you're lucky, you won't end up with paper-towel-pen. At best, you'll have an opaque, uneven mess. This is another thing you'll just have to get a feel for - I usually take about 1-2 seconds to go from one end to the other - could possibly go a bit more, but not much. If it's at all tacky, you're probably making it worse - and split seconds from the aforementioned mess since this stuff dries so quickly.
There you have it - this is what works for me (so far). I'm not an expert, and I have not been paid for this endorsement...
--Blake
After doing plenty of reading around here, I mixed up my first batch (which has now become my starter). I tried applying it straight from the can - it was super thick, but gave a _great_ depth right away! Bad thing was, it was too thick and dried too fast - it was a lumpy / ridgy mess, and even de-laminated from the pen when I tried to sand it off! But I could see the promise in it, so I tried again. I got a small plastic bottle with a narrow applicator tip from Rockler (which thankfully has not dissolved in the Acetone - see note below) and used that to mix my application mix. I went quite a bit thinner - more like think CA. It seemed to work OK... sometimes. Worked great on long flat surfaces (think B2B pens), but any time I had any kind of tight curves, I lost the finish in that area during sanding. Took me a while to put it together that that is where it was occurring - I just kept noticing that I didn't have a good finish after I finish sanded. I don't know if there's another way around that. At some point, I always noticed something wrong, and sure enough, there would be a few spots with no finish left. Anyway, I tried applying more finish in the problem areas and _lightly_ sanding - it worked, but took forever. I finally decided to try a new mixture - I went about the consistency of medium CA this time, and I think it's working _lots_ better!
For those interested, here's my procedure:
1.) Sand through 4000 MM.
2.) Slow lathe down - I have a Jet midi and go the next-to-slowest speed, which I believe is about 800.
3.) Using a folded over paper towel (I like to get a long, narrow strip as it takes many light applications), apply a couple of drops of the mixture and wipe on from one direction.
4.) More drops, wiping on from the other direction.
5.) Apply ~10-15 coats.
6.) Start sanding again with MMM 2400 or 3600 - depends how many "ridges" you have. It takes a bit of getting used to it, but I have reduced the ridge height and been able to start with 3600 or 4000 sometimes. (ridges are relative - it should be pretty smooth when you're done applying plexi)
7.) It does sometimes help to sand lengthwise at the lower grits
8.) Sand through 12000.
9.) Maguire's swirl remover
Random tips:
- Don't use vinyl gloves! Acetone is also a solvent for vinyl, apparently!
- Experiment with the mixture viscosity - too thin and you won't leave behind enough plexi. Too thick and it turns into a mess. Unfortunately, I don't have anything more concrete than that.
- Quickly wipe on the finish and _leave_it_alone! Can't stress this enough - one time, you'll think that you can use the acetone to smooth out the surface without having to sand as much (at least I did!) - if you're lucky, you won't end up with paper-towel-pen. At best, you'll have an opaque, uneven mess. This is another thing you'll just have to get a feel for - I usually take about 1-2 seconds to go from one end to the other - could possibly go a bit more, but not much. If it's at all tacky, you're probably making it worse - and split seconds from the aforementioned mess since this stuff dries so quickly.
There you have it - this is what works for me (so far). I'm not an expert, and I have not been paid for this endorsement...
--Blake