Can you reuse terracotta tiles beside older grout still on them? Most of the loose grout has be chemically removed, but it won't...

Most of the loose grout has be chemically removed, but it won't all come rotten easily minus chiseling. I don't want to risk breaking the tiles, since they are still in polite shape despite their almost 20 year age. If I had to buy investigational tiles, there would be a difference surrounded by wear and sheen, so this is why I want to keep the unproved tiles. Can I retile them with some mature grout still on?
My cabinet are very soon painted white and...
Answers:    I'm worried about that dated grout breaking down some day, and cause a headache.
I'm also worried that the color of the old grout will never clash any new grout.
Can't you particularly sand them down with fine sandpaper?
What chemical did you use to remove the feeble grout? Maybe the tiles need a second treatment.
Did you try soaking them within CLR or vinnegar?
Is at hand anything i can put in...
do you mean grout or thinset....if only a small amount of thinset it should be fine to redo................