How To Remove Grout From Shower Base. Fill a spray bottle with half vinegar and half water. Start in the middle of your shower and move your way out.
Do the vertical lines first before moving onto the horizontal lines. If dried grout reside does harden onto the tile you can try to remove it using vinegar a chisel or a diluted sulfamic acid solution. If this is the case it will be necessary to scrape it away.
Steps to remove the grout.
Cleaning grout or mortar from a tub use a wooden popsicle stick or tongue depressor to carefully pop off dried blobs of grout or mortar. The easy way to get rid of that old dirty grout. Allow the paste to set for a few minutes to work its magic and then give the grout lines one more agitating scrub for good measure. Do not force it.