How would you clean this?

[Neemer]

The good news is my renovation project is complete. The not so good news is I have a little bit of cleaning up to do, and my initial thought on how to approach these stains (or whatever you’d call them) isn’t working. Before I get too into this, I’d like to get a little feedback on how I can approach this without spending all day in a fruitless effort.

The picture shows what I’m trying to remove. Those whitish stains are mortar that dripped down the side as the coping was being installed. I thought scrubbing with a sponge would get them...nope. I haven’t done much work with fiberglass and I don’t want to use something too abrasive.

Suggestions?

 

[sktn77a]

Is it rough like mortar, or is it smooth like a stain?

 

[Texas Splash]

Start easy and work your way up. Perhaps a water/acid 3/1 ratio with some elbow grease at first with a mild pad. Nothing too abrasive. Once it dries if it returns, try a Magic Eraser. If that doesn't work, you may have to go with a wet/dry sandpaper, something like a 1500-2000 grit. Keep it really wet and take your time. In all cases, try a small area first then let dry to ensure you are pleased with the results. I will also mention there are some fiberglass-specific rubs/cleaners out there. So if you are concerned about any of those items you could try a marine shop or something similar.

 

[Neemer]

Mostly rough. The thickness varies.

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Great input, Splash. Thanks!

 

[PoolGate]

You could use vinegar as your acid too.