Meguiars unigrit finishing discs wear out too fast

[turbo_911]

Hello everyone,

I have bought 6 inch and 3 inch Meguiars 1500/3000 finishing disks, and decided to test out with 3 inch as they are cheaper and if I ruin them not a big deal. I used a couple and was able to sand whole quarter and rear bumper on a coupe with no problem and then I noticed it started to wear out. I expected that (that test was 1 month ago)

Yesterday, I as detailing customers car and I needed to sand down bottom portion of the door as it had way to many scratches. The area was around 6x14 inches. I used 3 inch disk and as I started to sand down the surface, I noticed it is not cutting. I worked it a bit more and still no effect. I cleaned it and tried again and still nothing, it was just making more scratches but wasn't sanding down clear coat like it did when I first tried it on the other car. I took out another disk and same story. I even followed the tutorial Mike Phillips posted with still no luck. Seems like it either clogs too fast or doesn't cut at all.

I have no idea what to do, and not sure if I should try the 6 inch one but then I was thinking if it would give me same effect, I won't be able to return them as I used one disk. I don't mind trying, its just I payed so much and for some reason it stopped working for me, where it worked fine in the beginning and I was satisfied with the results.

Anyone have any ideas or thoughts what could be wrong? I tried at different speed settings from 2-4 and with one to two mists of water.

Thank you.

[Michael Stoops]

Re: Meguiars unigrit finishing discs wear out too fast

It sounds as though you've basically gone through the useful life of the smaller discs. They really are for spot repair and you've already done a quarter panel and rear bumper with one of each grit! Definitely switch to the 6" discs - you should be able to do the whole car with a single 3000 grit finishing disc after using a couple of 1500 grit discs first.

[turbo_911]

Re: Meguiars unigrit finishing discs wear out too fast

It sounds as though you've basically gone through the useful life of the smaller discs. They really are for spot repair and you've already done a quarter panel and rear bumper with one of each grit! Definitely switch to the 6" discs - you should be able to do the whole car with a single 3000 grit finishing disc after using a couple of 1500 grit discs first.

Sorry, I guess I confused you. With the first one I was able to sand down whole quarter and rear bumper, that's when I did a car about a month ago. Right now I am doing another car I need to sand bottom portion of the door 6x14 inches and I've tried two brand new discs they start sanding fine and then they don't sand at all. Basically 2 discs on 6x14 area compare to when I did whole quarter with one disc. That's why I was wondering if I am doing something wrong or it's the disc fault or some technique I should follow?

[Flash Gordon]

Re: Meguiars unigrit finishing discs wear out too fast

Sorry, I guess I confused you. With the first one I was able to sand down whole quarter and rear bumper, that's when I did a car about a month ago. Right now I am doing another car I need to sand bottom portion of the door 6x14 inches and I've tried two brand new discs they start sanding fine and then they don't sand at all. Basically 2 discs on 6x14 area compare to when I did whole quarter with one disc. That's why I was wondering if I am doing something wrong or it's the disc fault or some technique I should follow?

Have you tried rinsing off you disk? If so, how do they feel. You should definately be getting more use out of them then what you decribe. Also, make sure your surface in clean of debris

[Michael Stoops]

Re: Meguiars unigrit finishing discs wear out too fast

Sorry, I guess I confused you.

OK, gotcha now!

Have you tried rinsing off you disk? If so, how do they feel. You should definately be getting more use out of them then what you decribe. Also, make sure your surface in clean of debris

Good points. Another thing to consider is what's on the surface of the paint to start with. The sanding/finishing discs have a protective coating on them that needs to be broken down first (the induction process, as it's known). This can be done quickly by simply rubbing two discs of the same grit together before use. But beyond that, if the paint has any durable polymers on it, like a quality synthetic sealant, that alone can seriously compromise the cutting ability of the disc. Crazy as it sounds, you can sand for quite some time without making any real progress if the surface has a nice coat of polymer on it. It really doesn't take much, and it can be quite a surprise when first experienced. Give the surface a wipe down with isopropyl alcohol or similar try the area again. Also, run the discs against a microfiber towel for a second or two to help remove any loose material they may have picked up.

Obviously you got good mileage out of the discs on the other car you did, so it's not the discs themselves, and it's not your technique. We're willing to bet it's something on the paint on this particular car.

[Flash Gordon]

Re: Meguiars unigrit finishing discs wear out too fast

OK, gotcha now!



Good points. Another thing to consider is what's on the surface of the paint to start with. The sanding/finishing discs have a protective coating on them that needs to be broken down first (the induction process, as it's known). This can be done quickly by simply rubbing two discs of the same grit together before use. But beyond that, if the paint has any durable polymers on it, like a quality synthetic sealant, that alone can seriously compromise the cutting ability of the disc. Crazy as it sounds, you can sand for quite some time without making any real progress if the surface has a nice coat of polymer on it. It really doesn't take much, and it can be quite a surprise when first experienced. Give the surface a wipe down with isopropyl alcohol or similar try the area again. Also, run the discs against a microfiber towel for a second or two to help remove any loose material they may have picked up.

Obviously you got good mileage out of the discs on the other car you did, so it's not the discs themselves, and it's not your technique. We're willing to bet it's something on the paint of this particular car

As long as you can front me $$$ (in the very rare case we may be wrong) then put me all in

[turbo_911]

Re: Meguiars unigrit finishing discs wear out too fast

Have you tried rinsing off you disk? If so, how do they feel. You should definately be getting more use out of them then what you decribe. Also, make sure your surface in clean of debris

Yes, tried rinsing it off and wiping with terry towel and it feels like its new lol. The whole car was claybarred and surface is smooth. On the first door, I tried to detail with M105 and Megs yellow pad, did 3 passes and not everything was removed that's when I though I would sand it down but it wouldn't sand. I thought its the polish, and decided to sand the second door with new disc and same scenario.

OK, gotcha now!



Good points. Another thing to consider is what's on the surface of the paint to start with. The sanding/finishing discs have a protective coating on them that needs to be broken down first (the induction process, as it's known). This can be done quickly by simply rubbing two discs of the same grit together before use. But beyond that, if the paint has any durable polymers on it, like a quality synthetic sealant, that alone can seriously compromise the cutting ability of the disc. Crazy as it sounds, you can sand for quite some time without making any real progress if the surface has a nice coat of polymer on it. It really doesn't take much, and it can be quite a surprise when first experienced. Give the surface a wipe down with isopropyl alcohol or similar try the area again. Also, run the discs against a microfiber towel for a second or two to help remove any loose material they may have picked up.

Obviously you got good mileage out of the discs on the other car you did, so it's not the discs themselves, and it's not your technique. We're willing to bet it's something on the paint on this particular car.

Hmm, good points and thank you for reply.

As stated above one door was polished with M105 another wasn't and didn't had any sealant or anything, it was just claybarred. The car haven't seen wax or wasn't detailed in a long time.

I will try to work it a bit more and try a new disc and will see what happens or I might just try the 6 inch 1500 grit finishing disc instead of 3000.

[Michael Stoops]

Re: Meguiars unigrit finishing discs wear out too fast

As stated above one door was polished with M105 another wasn't and didn't had any sealant or anything, it was just claybarred. The car haven't seen wax or wasn't detailed in a long time.

I will try to work it a bit more and try a new disc and will see what happens or I might just try the 6 inch 1500 grit finishing disc instead of 3000.

As crazy as this sounds, even Quik Detailer can be enough to dramatically slow down the removal of that protective layer on the discs, and you'd be amazed at how long you can run the thing against the paint while doing very little actual "cutting". Wipe down the panel with IPA and give it another shot.

[turbo_911]

Re: Meguiars unigrit finishing discs wear out too fast

I did the wipe down, and tried 6 inch 3000 disc, was managed to sand down whole door, fender and when started to sand quarter (on a 4 door) it seemed like it wasn't sanding anymore, barely. Does that sound about right? Or it should last a longer?

[Michael Stoops]

Re: Meguiars unigrit finishing discs wear out too fast

If you're starting with 3000 grit as opposed to using 3000 as a follow up to 1500 then you may well see it giving up sooner - you're in contact with a lot more surface area this way, which will effectively shorten the life of the disc. Also, how much are you trying to remove with 3000? If you're really working an area for a while and making a very noticeable change in the surface, then 3000 may be too fine a grit to start with - it alone shouldn't be taking off much of anything, really. It's more for refining your earlier sanding efforts.

Lastly, how often are you cleaning the disc? You should either spray it liberally with water or quickly spin it against a microfiber towel to regularly clear it of any loose material.

[turbo_911]

Re: Meguiars unigrit finishing discs wear out too fast

I was mainly sanding to get rid of small scratches, because clear coat was really hard and it was taking a lot time to get the other side of the car perfect so I decided to sand down this side. I was cleaning it after every 2x2 area.

I guess I should try using 1500 first and see how long it will last and then use 3000 to refine sanding marks after. I will post feedback when I will work on another car.

Thank you Michael for suggestions and feedback, I appreciate it.