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Polishing compund and sanding paper #2949517 02/20/20 02:46 PM
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Iljitsal Offline OP
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I have an older Roland HP-5700 which has a high gloss finish. The laque looks like high gloss polyester./ polymeer.

The piano has some light but also some deepeer scratches. I have tried on a spot with sandpaper 600, 1000, 1500 , 2000, 2500 and 3000.
All the sratches are completely gone but now it is missing the high black gloss At the moment it is more of satin black finish and the black is also more grey.
When you make it wet the gloss is back untill it is dry.

How can I proceed the next step? Do I need even more fine sandingpaper like 4000, 5000 etc. or do I need at this stage special polishing compounds?

I hope some members here have experiance with sanding and polishing of this kind of finish. Which brand from polish compound is adviseble or even maybe several in different grains.

Sanding is best done dry or with water?


Kawai MP11SE, Bechstein grand (100 years), Garritan CFX, Ivory American Grand, Pianoteq 6 studio
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Re: Polishing compund and sanding paper [Re: Iljitsal] #2949522 02/20/20 03:02 PM
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Rickster Offline
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I'm not a pro (by any means) but it seems to me you need the polishing compound at this point, and perhaps a high-speed buffer/polisher. 3000 grit sandpaper is pretty fine. Going to an even finer grit for sanding is still not going to achieve the result you are looking for, which is that high-gloss finish, although the finer grit sandpaper would help reduce the effort needed for the final polishing process.

The greyish satin look you are seeing is the very fine scratches in the finish created by the sanding process, in an effort to get rid of the scratches.

You might take some medium polishing compound and try hand rubbing the polish, and check the results. There are lots of info on this process online. But again, I'm no pro.

Good luck!

Rick


Piano enthusiast and amateur musician: "Treat others the way you would like to be treated". Yamaha C7. YouTube Channel
Re: Polishing compund and sanding paper [Re: Iljitsal] #2949529 02/20/20 03:23 PM
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Iljitsal Offline OP
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Rick thanks for your reply! I don't have any rubbing compound but I tried with some tootpaste and it is already better. Meaning indeed as you said that compound is very needed. 3M has some very good compounds but I don't know which one or more I should use. By the way, I have a Bosch angle grinder with variable speed. I use it for all kind of jobs and the variable speed make it perfect for polishing and sanding however I heard excenter sanding machines are better for sanding.

About the compound maybe indeed first medium and then super fine but whch are often used for the high gloss piano laque which is different then car laque?


Kawai MP11SE, Bechstein grand (100 years), Garritan CFX, Ivory American Grand, Pianoteq 6 studio
Re: Polishing compund and sanding paper [Re: Iljitsal] #2949539 02/20/20 03:52 PM
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Rickster Offline
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I have a feeling the finish on your Roland is likely a polyester clear coat. If so, it is a hard, tough finish. I doubt they used lacquer on the Roland, but I could be wrong. If the tooth-paste is already making an improvement, then yes, your next step is the polishing compound. But it would be best if you knew for sure what kind of finish you had (polyester or lacquer) before deciding on the best polish to buy.

I'm a fan of Roland equipment!

Good luck!

Rick


Piano enthusiast and amateur musician: "Treat others the way you would like to be treated". Yamaha C7. YouTube Channel
Re: Polishing compund and sanding paper [Re: Iljitsal] #2949603 02/20/20 08:16 PM
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Jack Moody Offline
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If it is a high gloss poly finish, dont use 600 grit.Start with wet 1500 or 1000 if it needs it. USE A BLOCK
Then 1500 grit wet. Dont sand too much. If you wet sand correctly, you will only level the high spots with the low spots. This is why you can only correct shallow imperfections. If its deep, drop fill it with CA glue. I wont explain, unless you need me too.

Get a DA polisher from Harbour Freight, if you plan to correct a large area. If you plan to use a DA, let me know and I'll give more details. Using the grinder is possible but requires more skill.

Buy Meguires Ultimate Compond. The lubricants make it easier to work than some others.
Meguiar's G17220 Ultimate Compound, 20 Fluid_Ounces https://www.amazon.com/dp/B06W5HCZ9M/ref=cm_sw_r_cp_apa_i_u3XtEbZEG3040
They usually have it at Walmart. Use a microfiber cloth and buff it like crazy, while keeping it slightly wet with compound. You can also buy Ultimate polish to finish with, but it's optional.

I would start with compound on your dull area. Buff it and it will get glossy, but may have scratches from the 600 grit. If so, wet block sand it for a bit with 1000, then 1500 and buff again.

Use 3m sandpaper and KEEP YOUR SAND PAPER CLEAN, buy dipping in water frequently.

You can usually buy sandpaper 1 sheet at a time at O'Reillys. Ask at the counter and they will get it from thr back.

You might like the photos in my thread here:
http://forum.pianoworld.com/ubbthre...h-before-after-pictures.html#Post2939708




Last edited by Jack Moody; 02/20/20 08:25 PM.
Re: Polishing compund and sanding paper [Re: Iljitsal] #2949607 02/20/20 08:32 PM
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By the way, if you see color on the wet sand paper, you are in trouble. You should have no problem with sanding through the clear if you start with 1000 or 1500 and work reasonably.

Poly finish is typically pretty thick. Are you planning to correct the finish on the entire piano?

I'm glad to help you if you have questions.

Re: Polishing compund and sanding paper [Re: Rickster] #2950076 02/22/20 09:52 AM
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Iljitsal Offline OP
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Thanks so much Rick and Jack for your great effort to help! Really appriciated!

The finish is indeed a very hard black polyester coating. from maybe 0.5mm thickness. You have given me some incredible usefull tips for the polishing. I am very sure that it will work because there was already an improvement with simple toothe paste after I sanded with 3000 grid. But now I will try with wet and dry and keeping the paper clean. Later with the compound. Because I am in the Netherlands the compound from your link is not available here but 3m has also some rubbing compounds from basic, medium fine and extra fine. My question is, do I need all 4 of these compounds with different grane or just the fine or extra fine.
I have read already very good things about it but unfortunately these compounds are pricey frown


Kawai MP11SE, Bechstein grand (100 years), Garritan CFX, Ivory American Grand, Pianoteq 6 studio
Re: Polishing compund and sanding paper [Re: Iljitsal] #2950106 02/22/20 11:24 AM
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I would start with a rubbing compound. I have seen a good auto paint shop use this
https://www.amazon.com/dp/B002SRZQV6/ref=cm_sw_r_cp_awdb_t1_gkuuEbFE5VD93

If you use a DA polisher, then you use different pads for compounding and polishing. A compounding pad used with the compond makes it much faster.

If you work with a cloth in hand, you will remove material much slower.

The compound would likely produce a finish that would please you. If not, go back and buy a polish.
I went to a micro polish level on this car. Honestly, its overkill and it would be a lot of work by hand.

[Linked Image]

If worked correctly, the compound that I listed will take it to this level.

[Linked Image]

Are you planning to do the whole piano? It would take me several hours to do an upright piano with a DA polisher. It would take even longer if I had to fill spots to repair damage or deep scratches. I'm meticulous though, so I may be slower than some.

For repairs, I like black CA glue. I can tell you more if you need to know.

Re: Polishing compund and sanding paper [Re: Iljitsal] #2951770 02/26/20 10:12 AM
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Iljitsal Offline OP
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Jack thanks so much for your help! I have meantime ordered a set of different rubbing pad's and 2 bottles of 3m polish. One is a high gloss machine polish and the other is a fine cut compound. I just got them and could not wait to try it by hand on a small area. Results are perfect now.
First remove the scratches with dry and wet sandingpaper. Grain 1000, 1500, 2000, 3000 and then the fine cut compound. Afterwards the high gloss machine polish. It looks like new!

But I am very interested how you do it with the CA black glue. I also can buy black 2 component polyester but that is not liquid. Can you make the CA black glue shining?

By the way, nice car you have there!

Last edited by Iljitsal; 02/26/20 10:13 AM.

Kawai MP11SE, Bechstein grand (100 years), Garritan CFX, Ivory American Grand, Pianoteq 6 studio
Re: Polishing compund and sanding paper [Re: Iljitsal] #2951816 02/26/20 12:19 PM
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Jack Moody Offline
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Originally Posted by Iljitsal
Jack thanks so much for your help! I have meantime ordered a set of different rubbing pad's and 2 bottles of 3m polish. One is a high gloss machine polish and the other is a fine cut compound. I just got them and could not wait to try it by hand on a small area. Results are perfect now.
First remove the scratches with dry and wet sandingpaper. Grain 1000, 1500, 2000, 3000 and then the fine cut compound. Afterwards the high gloss machine polish. It looks like new!

But I am very interested how you do it with the CA black glue. I also can buy black 2 component polyester but that is not liquid. Can you make the CA black glue shining?

By the way, nice car you have there!


Man! I am so excited to hear that it is coming out nice!!

I'm sorry, but I'm not familiar with 2 components poly.

CA glue repairs are a little more difficult than polishing. Actually, a mediocre repair is easy, but it takes patience and time to get them near perfect. In some situations a mediocre repair is just fine, btw. They certainly look better than a huge missing chunk.

I strive for near perfect results, though.

CA glue will be shiny (after buffing? and should match your poly really well. Black CA glue is easiest and gives very nice results. If you want perfect, again not necessary, I would use black CA for a couple of layers and then clear. This will ensure that it looks great underneath and has a little more depth. I came up with this myself, and it's near overkill, but it works. No difference would be seen from 3' away, but I made repairs that I cant find from 1 foot away.

Here are some points to remember
-CA should sand down faster than poly. It's slightly softer.
-CA takes many hours longer to dry than you would expect. Give it ample time or use very thin coats and spray it with an accelerator between coats. It must be dry before you work it!
-If a repair doesnt go well, the CA likely wasn't dried properly.
-Dont sand or polish the surrounding are before a repair. Leveling the CA is the key. You will lose a little of the surrounding finish. So, finish repairs and then polish.
-I prefer the expensive gluboost brand. Especially if you use an accelerator.
- if a flaw is through the black color but just barely, I sometimes dig it a little deeper with a razor.
-If the flaw is still black, you can use clear CA and the finish color will be exact.
-I level with a razor at first. This is the only real tedious part. Get the level right for superior results. Use a block to level it!
-Apply tiny bits of CA glue. I've used a tooth pick point. Make sure there are no low spots, but too much CA will make it take longer. Apply CA slowly and methodically.

Here is the best video. I dont use course sand paper though. It takes longer, but I think it's safer and better. His idea about making small sanding blocks is superb! glue some up just like he recommends.

Re: Polishing compund and sanding paper [Re: Iljitsal] #2951818 02/26/20 12:21 PM
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Re: Polishing compund and sanding paper [Re: Iljitsal] #2951821 02/26/20 12:27 PM
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This shows the gluboost accelerator and gives another example of a repair.

Please let me know if all of this is helpful.


Re: Polishing compund and sanding paper [Re: Iljitsal] #2959482 03/22/20 08:47 AM
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Iljitsal Offline OP
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You have wonderful videos Jack and thank you so very much! People like you willing to help others with questions and problems is simply amazing!
I did not know about the CA glue Jack! This is super interesting stuff because the problem is indeed always the pigments. I will try this glue. Super video!

My piano is finished in the meantime and it is like new. Because all the hammers where cracked and one broken, I removed it and used the cabinet from the Roland for my Kawai MP11SE. Was several weeks work but the result is stunning.

I used 2K polyester compound in black and with this you can repair everything. Sanding is the hardest part. I use tape around it for not damaging the surface around and then sand with every time finer grains. Afterwards I polished it with 3M polishing compound and a polishing machine with variable speed. I used 2 different grains in the compound. Fine and ultra fine machine polish.


Kawai MP11SE, Bechstein grand (100 years), Garritan CFX, Ivory American Grand, Pianoteq 6 studio

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