Grinding/Polishing Indian Limestone?

[efunc]

Hi all,

 

I picked up 12 Indian Limestone slabs which are black in colour for a givaway price on eBay. Unfortunately I didn't realise they were heavily weathered and the surface is silver/grey and flaking away sheets. As they're slightly riven I thought it must be possible to polish them to match my sawn/honed Limestone I have elsewehere. I don't want to acheive a high polish at all, but just remove some of the flakiness and smooth/seal the surface some more. Obviously a dedicated patio polisher is out of the question but I've noticed you can buy 4" diamond discs in various grades quite cheap for polishing stone and concrete. I've also seen this wet polisher quite cheap, but don't want to buy another tool either given that the limestone only cost me £20:

 

Wet Polisher

 

I do have Kestral Das-6 Pro Dual Action (random orbital) polisher I use to compound my car bodywork. Would a diamond disc fitted to my DA polisher with a thoroughly wetted stone acehive any results?? Das-6 Pro

 

Failing that, I could get a basic angle grinder if that can be used perfectly flat to the stone face. Here's the limestone laid as coping stones in the dry:

 

 

and once wet:

 

 

 

Edited June 12, 2020 by efunc

[bassanclan]

I have the exact same polisher as you and used a diamond disc to Polish up some slate slabs, so give it a go.

[PeterW]

You can't recover the colour on black limestone without using a dye or re-splitting them - you may be just as quick buying one of the limestone restorers and sealers.

 

https://www.azpects.co.uk/products/easyseal-back-to-black.aspx

[efunc]

5 hours ago, bassanclan said:

I have the exact same polisher as you and used a diamond disc to Polish up some slate slabs, so give it a go.

Thanks! Do you have the Kestral Das-6, or the water fed one? And if so, which discs did you use?

[efunc]

4 hours ago, PeterW said:

You can't recover the colour on black limestone without using a dye or re-splitting them - you may be just as quick buying one of the limestone restorers and sealers.

 

https://www.azpects.co.uk/products/easyseal-back-to-black.aspx

Yes, very good point. However, I see them as separate issues and the colour fading is less important than the flaking. I have other limestone which I think is very similar, but it's honed, so seems much more resilient and less porous. I was thinking I could stop the new slabs disintegrating by polishing them down a bit. I might then use a sealer, and even the colour restorer, but I'll cross that bridge later. 

[bassanclan]

I only have the DA 6 car polisher, I can't remember exactly what I did, but I think I used my angle grinder with a stone grinding disc to get it somewhere near and then finished with the DA polisher. 

 

You are working with a different material, so I would say start with the DA polisher, but go coarser as you needed it, at least on the first stone.

[efunc]

9 hours ago, bassanclan said:

I only have the DA 6 car polisher, I can't remember exactly what I did, but I think I used my angle grinder with a stone grinding disc to get it somewhere near and then finished with the DA polisher. 

 

You are working with a different material, so I would say start with the DA polisher, but go coarser as you needed it, at least on the first stone.

Excellent! Very encouraging. If you've got examples of your experiment I'd love to see the pics. I'll go and hunt for some diamond discs that will fit my backing plate and give it a whirl. Thanks

[bassanclan]

I haven't got any photos I'm afraid. Try running a normal sanding disc over it first to see how it reacts.

[efunc]

Good idea, no harm in trying that first I suppose. Thanks