Here I’m going to talk about the best way to remove silicone from a bath or shower, and more importantly, how NOT to do it.
First how not to do it. Thanks to painful personal experience, I highly recommend not using WD40 despite what you may have read on websites or watched on YouTube. Speaking as someone who has worked with a lot of silicone sealant over the years in the roofing, guttering and fascia business, as well as in my home, WD40 was the worst experience I have ever had removing silicone, mastic or caulking, ever. Much better was PVCu Solvent cleaner as advised by my plumber in the first place, to whom I wish I had listened. Isopropyl alcohol is also the king of cleaning agents if you want to make sure any surface is 100% clean.
In case you haven’t seen it, this is what happened to my new silicone sealant after trace elements of WD-40 were left behind after cleaning. It’s just not worth the risk.
How to remove silicone sealant
- Buy an extendable flat bladed flexible snap off knife like the one in the picture below.
- Knock off the extremely sharp edge of the cutting blade with a couple of passes with abrasive paper down the blade, this helps to stop the keen overly sharp edge biting into any plastic or enamel coating and scratching it.
- Wear some safety glasses, extend the blade to an inch or two, and start cutting the silicone sealer (mastic or caulking) where it meets the tiles or bath. Start shallow and gentle, slowly get deeper.
- This part is optional, but my plumber highly recommends the use of PVCu solvent cleaner as an agent to help weaken the silicones bond. A frame cleaner like this is used by fascia fitters and window installers to clean PVCu and remove grease before applying silicone. When applied liberally to existing silicone it loosens the grip slightly, making it easier to rub or scrape off. A word of warning, test this on a small unseen part of the bath or shower before applying liberally with a cloth in case of a reaction. I did not suffer any sort of reaction, my plumber says he has not either, but better safe than sorry.
- Now use the knife again to scrape out, and off, any remaining silicone, applying more PCVU cleaner if necessary to help things along.
- Because the frame cleaner is solvent based it should evaporate or flash off by itself with time, but you can help it along by using a clean dry cloth to soak up anything left behind. And, because frame cleaner is used to clean surfaces before silicone is applied, as long as you let it dry you know it will not affect your new sealant after you apply it.
- Once you’re happy it’s totally dry, apply your new bathroom sealant.
- If you didn’t use PVCu frame cleaner opting for elbow grease alone, clean the surfaces of the tiles and bath or shower with Methylated spirit or better still Isopropyl Alcohol if you have it, prior to applying the sealant.
Silicone removal kit – In my opinion this is pretty much the only kit you need to remove old silicone from a bath, shower or sink. I prefer to knock of the very sharp edge of the blade with a few light strokes of sandpaper to stop any initial scratching, especially with plastic or enamel baths. I have never found a silicone removal tool that beats a simple snap off blade craft knife.
Removing silicone with WD40
Why is removing old silicone or caulking with WD40 such a bad idea? Well WD40 does peel off old silicone, and it does do so much better than any product I have ever purchased over the last 30 years. But, and here’s the rub. Unless you can be 100% sure you have cleaned away every last drop or smear of WD40, it can, and probably will, react with your new sealant. This could be either immediately, a day, or even a month later. This is very unfunny.
It started to ruin my new silicone sealant after a few days in a small section, then spread over the remaining weeks. I thought I had been very thorough cleaning the WD-40 off afterwards, even though getting down into the gap between my bath and tiles was a little tricky. And this is almost certainly why professional silicone sealant removers are not based on WD40, logical when you think about it. I have since re-sealed my bathroom using PVCu frame sealant as an aid to silicone removal, and had no problems at all.