Absolute Black and muriatic acid

[jmc]

My tile guy (former!) was using muriatic acid to remove grout from the backsplash and did not cover the absolute black leathered countertop. He taped around the stainless cooktop with blue painters tape to protect it. Basically he acid-washed the granite and when he removed the blue tape the countertop underneath looks significantly different than the rest. It is lighter and ashy looking (the original look). I have tried many many techniques and asked several professionals in the area. Two highly regarded stone guys have inspected and tried some things. No one can figure out how to return the granite to its original state. or even blend the line in. Here is a list of what I have tried:
acid wash the lighter spots near the stove
penetrating enhancer
lots of acetone
lacquer thinner with steel wool
black wax?
baking soda
mr. clean
sealer
bar keeper's friend
bleach
clr

also: The most experienced guy confirmed that his opinion is that it is legitimate absolute black.

Thanks for any ideas!

[Dan R.]

Try one of these (in order of ease and success probablity)
1. Aqua Mix Enrich N Seal (available at Home Depot ($50/qt, 1 will be plenty)
2.Tenax products: Tiger Ager or possibly Uniblack.
3. 50% Mineral spirits and 50% boiled linseed oil. This will take some patience and some elbow grease.

Did the Acid make it Lighter?
If so, I am confused about your remark of trying to acid wash the lighter spots near the stove.

Your tile setter needs some lessons.Acid indoors is dangerous and uncontrollable.

[Stone Dude]

penetrating enhancer - Too dense, even if it helps, it won't last long
lots of acetone - This will only remove residue from the surface, not repair an etch
lacquer thinner with steel wool - This will only remove residue from the surface, not repair an etch
black wax? - This wears off quickly and should never be used to "fix" something
baking soda - What?
mr. clean - This will only remove residue from the surface, not repair an etch
sealer - If enhancer didn't work, what did you think sealer was going to do?
bar keeper's friend - This has acid in it, using acid to fix acid damage is not really going to work
bleach - Why?
clr - This has acid in it, using acid to fix acid damage is not really going to work

they just threw a bunch of random stuff at it without even understanding what those chemicals do. Acid, solvents, wax, enhancer, impregnator, Bleach, I mean this is a really bizarre list.

Legitimate or not, Black Absolute can be damaged by muriatic acid if it sits on the surface long enough. This damage is often not reversible, but sometimes you get lucky.

It's also nearly impossible to help without pictures.

[Brian Briggs]

It could also be a case of dyed AB as well. The acid will turn AB grey in a heart beat if dyed. If that is the case try the Tenax Uniblack to darken the entire surface. I have never done this, so run test pieces first

[Shiny Alex]

Surely if the Tiler has damaged it, he should be paying for a replacement? Or does it work differently over there?

[Marblecity]

Honestly it sounds like you should return the finish back to zero. Plastic the walls, cabinets, and floors and releather and feather out the area. Clean all the tops with a sealer stripper and reapply a textured stone inhancer. It sounds like alot but my shop and I have done this a few times usually takes a day if you start early and keep a steady pace. We use spray bottles and split up in teams but we take on whole houses at times. Practice your techniques first and plan your steps.

[Jonathan]

Agree, Re-finish it see what it does. Or faster yet - replace it.

[crisco]

Hmm. I would mix mineral spirits with black epoxy resin color and dab on a camouflage type layer. I've have tons of luck with minwax stains. Then if it's leathed, I'd probably hit it when the color dries with a varnish or clear lacquer. After the shell hardens I'd prob try 0000 steel wool to match the shine to matte. But I wouldno tell anyone this. If anyone knew, I'd suggest a replacement by liability.

[Matt Lansing]

Well that's some interesting advice...

Some Absolute Blacks can contain calcite and the acid most likely reacted with the calcite present in the stone and basically "burned" it.

It may not be possible to reapply more acid to even out the finish as it will continue to burn the already burned areas making them lighter.

Only solution would be to pull the tops, regrind to a new surface, and then brush the stone back to an original finish. Yay...

Unfortunately you can't brush a surface to a good result in the house, it takes far too much water to keep the brushes cool to be possible on site.

[Voges23]

It could also be a case of dyed AB as well. The acid will turn AB grey in a heart beat if dyed. If that is the case try the Tenax Uniblack to darken the entire surface. I have never done this, so run test pieces first

Is there a difference between Uniblack and black Pectro?

[Rick George]

The Uniblack is a black dye designed to penetrate black granites where the Pectro Black will not penetrate as deeply and is more of a topical to help hide microfissures in darker stones. For this issue, I agree with Brian that you could try the Uniblack but I do suggest testing this first just like Brian said.

[Kowboy]

It doesn't take acid to wash the color out of some Absolute Black. Water will do the job, as demonstrated by this fountain in the Chicago Amtrack station:

IMG_5153.jpg (328.15KiB)Viewed 510 times

[Joe Little]

my .02
wd-40 is super thin and will go in the stone and bring back color , my not be enough by itself.
I had to do a similar one years ago before tepox , and used a sharpie and wd , then scotch brite pad to blend it in.
Lite water and green scotch bright pad will help the surface color back some on its on..

But the Uni-black may be too black ( I would recreate a sample and test in the shop if I was going to attempt to
use it in a house ) and possibly cut it with acetone , and I'm not sure if it could be toned down any ( ask Rick or Brian at Tenax ).. as stated above.