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View Full Version : Acrylic Scratch Removal - dry, or wet! (no need to remove inhabitants)



JohnnyAirtime
09-28-2011, 02:11 PM
Well, as I occasionally scratch my 240gal Acrylic... I whine every time:cry:.

However, I know better these days and know it can be fixed or repaired. Still, once the scratch is there I know what it takes to remove it. LOTS and LOTS of elbow grease, with the tank empty and worse with the tank full of water and livestock ... However, knowing EVEN WITH water and corals/fish still within the tank it can be fixed.... No need to drain it!!!

So, "how?" you asking ... easy, read on;:coffee:

FIRST OFF; Give yourself lots of time, and patience.

SECONDLY; Buy this kit (or any Micro Mesh kit); http://www.amazon.com/MICRO-MESH-NO-HOLE-SANDING-COMBO/dp/B000H6JDDC/ref=sr_1_5?s=hi&ie=UTF8&qid=1317245659&sr=1-5

MAKE SURE to use something like a large MAG Float, or sanding block.
You MUST keep the sand paper or MM flat to the surface your sanding. Using your hand, or fingers will only make things worse.

THEN; Find the worst of the scratches and mark them on the outside with a grease pencil. You'll need to try a scratch or spot that isn't the front center of the tank! You don't want to learn your method is the wrong method, your first time around. I've seen people do worse damage.

Depending on how bad your scratches are, will depend on what grit pad you start with. The more course the pad, the more sanding you'll end up doing. If too course, it'll take a while to get the scratches to a point where they aren't visible. This will require you to work up through the grits to the final pad, or to where the scratch is gone and your micro scratches are no longer visible. I will test the acrylic with the smoothest grit pad, and work towards the most course to see where I can see the fine micro scratches. Once I see those fine scratches, I start with that pad. Usually a 3600g will be the one to start with (if you want to be sure you don't use too course a grit).

Take the 3600 pad, and sand in a direction perpendicular to the scratch. Don't do one small 1" square section as you don't want to take away too much acrylic in one small spot at a time. Make sure to feather back from the scratch about an inch or two, knowing that when you move up to the next grit... you'll feather back another 1/2" or so, and so on. Once the scratch is out, you'll then only work on your micro scratches until you can't see them. And wha-la... no more scratch. I'm forewarning you, this doesn't take 15min, or 30... or 60. More like ... hours. BE PATIENT!!

Of course, the marks with the grease pencil can be removed once you've sanded out the scratch, and the fine micro scratches.


For DRY sanding, you'd use a similar technique.;
Which is of course, an empty tank. ;) And you can use more course sanding grits. I usually use a wet/dry sandpaper. Starting at 220 or 320G and finish with 2500G (using 400, 600, 1000, 1500, 2000 in between). Final polishing with Novus 3, 2, 1 in that order. (For the wet sandpaper) I use a spray bottle full of water with a tad bit (a couple drops) of dishwashing liquid soap as a lubricant, works well. But be sure to wash out the tank really well once complete, you don't want any remains of that soap left behind.

For dry sanding; The key here is to ALWAYS sand perpendicular to the previous grit paper. So if you started with 220, and sanded horizontally... then, you'd sand vertically with 320, and horizontally with 400, vertically with 600... and so on. Each time you change grits, you want to WATCH the sanding marks and make sure you remove them in each direction BEFORE moving on to the next finer grit paper. If you do not remove them completely at each step before proceeding, you'll have to go back to that grit and start all over... otherwise you'll see those scratches.

Whatever you do when dry sanding, don't get lazy and sand in a circular motion. Trust me on this!!!

.... I hope everyone has a scratch free tank, due to the above helpful info!!! Any questions, let me know!

:bounce:

grimey
09-28-2011, 02:18 PM
Great write up.

Elias
10-22-2011, 06:55 AM
So the debris won't hurt the livestock at all?

JohnnyAirtime
10-23-2011, 07:08 AM
So the debris won't hurt the livestock at all?

Nope... the sanding "dust" is so minute you won't have a problem.

Elias
10-23-2011, 07:47 AM
Awesome well that is great to know. Thanks Johnny

CARDIFF REEF
02-11-2012, 07:09 AM
will it work on glass?

JohnnyAirtime
02-11-2012, 09:38 AM
will it work on glass?

"Sandpaper" does not work on glass. To polish glass, it's called Cerium Oxide.
... however, if you can "feel" a scratch in glass with your fingernail it's too deep for CO and must be grinded out first. THEN polished with CO.

It's not an easy task (not for the beginner DIYer), and the process can weaken glass as well as distort.

JohnnyAirtime
07-29-2012, 07:08 PM
.............
SECONDLY; Buy this kit (or any Micro Mesh kit); http://www.amazon.com/MICRO-MESH-NO-HOLE-SANDING-COMBO/dp/B000H6JDDC/ref=sr_1_5?s=hi&ie=UTF8&qid=1317245659&sr=1-5

THEN; Find the worst of the scratches and mark them on the outside with a grease pencil. You'll need to try a scratch or spot that isn't the front center of the tank! You don't want to learn your method is the wrong method, your first time around. I've seen people do worse damage.

Depending on how bad your scratches are, will depend on what grit pad you start with. The more course the pad, the more sanding you'll end up doing. If too course, it'll take a while to get the scratches to a point where they aren't visible. This will require you to work up through the grits to the final pad, or to where the scratch is gone and your micro scratches are no longer visible. I will test the acrylic with the smoothest grit pad, and work towards the most course to see where I can see the fine micro scratches. Once I see those fine scratches, I start with that pad. Usually a 3600g will be the one to start with (if you want to be sure you don't use too course a grit).

Take the 3600 pad, and sand in a direction perpendicular to the scratch. Don't do one small 1" square section as you don't want to take away too much acrylic in one small spot at a time. Make sure to feather back from the scratch about an inch or two, knowing that when you move up to the next grit... you'll feather back another 1/2" or so, and so on. Once the scratch is out, you'll then only work on your micro scratches until you can't see them. And wha-la... no more scratch. I'm forewarning you, this doesn't take 15min, or 30... or 60. More like ... hours. BE PATIENT!!

Of course, the marks with the grease pencil can be removed once you've sanded out the scratch, and the fine micro scratches. .............

I just wanted to note/update this thread, and this post...

I noticed some scratches in my 240G Reef Tank from using my Kent Marine (plastic) Scraper. Not too bad, but... noticeable by me. I think my scraper must have picked up something and just enough to put some scratches dead center of my tank.... so, I went back to what I know and how to remove these eyesores. As well, this tank's been up for a year and in the meantime, I've moved a snail out of the way and when it sucked onto the acrylic... the shell dug in and scratched the tank. UGH! So, I'll take those out too.

(AND YES, with ALL LIVESTOCK in the tank)

I started with the roughest micro-mesh. Equivalent to a 1500grit wet/dry sandpaper. Yes, it leave scratches behind!
Once I got out the scratches from the scraper.... I went to the next grit, and so on all the way to MM12000 grit (probably equivalent of 4000 grit wet/dry). I think it was about 8 steps, or 8pieces of MM (Grits of MM: 1500, 1800, 2400, 3200, 4000, 6000, 8000, 12000 - remember, this grit rating is not equivalent to standard wet/dry sandpaper)

I then decided to do the lower 3-4" of the tank (above sand bed), where I know the scraper picks up sand when I'm getting the lower 4" of the tank. I used again, the strongest MM grit. And it takes a long time to knock them down a bit... so I didn't go for perfect. "Just enough" to knock down the algae collecting deep scratches. And for the bottom 4" area, I'll skip every other grit to get it to a polish (it doesn't need to be so perfect, as you have to bend down to see what I'm talking about).

In fact, this works so good... I'll be using it to clean the algae once a week, yet... I'll use one of the more finer grits, so it's not noticeable (no sand marks). This way, it'll be as-if I'm polishing as I clean.

pictures don't show much, but it'll show just how easy it is
37101 37102 37103 37104

JohnnyAirtime
08-15-2012, 09:25 AM
I wanted to update this thread with a couple pictures to show what's possible (on a DRY tank).
Even though hard to see progress via camera, you'll get the idea;


Sanding and buffing on a 180gal, that had severe scratching on inside of tank;

37129

37128

37130

37126

37127

The Process (for severe and deep scratches)
STEP1 - Random Orbital sander, 220G
STEP2 - Random Orbital sander, 320G
STEP3 - Random Orbital sander, 400G
STEP4 - Random Orbital sander, 1500MM (400G)
STEP5 - Random Orbital sander, 1800MM (600G)
STEP6 - Random Orbital sander, 2400MM (900G)
STEP7 - Random Orbital sander, 3200MM (1200G)
STEP8 - By Hand, using block sander, 1200G
STEP9 - By Hand, using block sander, 1500G
STEP10 - By Hand, using block sander, 2000G
STEP11 - By Hand, using block sander, 2500G
STEP12 - Machine polish, Novus 3
STEP13 - Hand polish, Novus 2
STEP14 - Hand polish, final wipe, Brillianize (Novus 1)

Step 8, and 9 are critical to remove half moon marks from Random Orbital Sander.
MM stands for micro-mesh. Chart to correlate MM to standard grit, is here. http://www.sisweb.com/micromesh/conversion.htm

Hope this helps those who are ever considering sanding and polishing acrylic!!!

Elias
08-15-2012, 07:04 PM
That is awesome, the tank looks new again. Great job Johnny