We've lived in our house for over 17 years. We also live in an area with super ridiculously hard water. Our shower (well, the whole bathroom) was newly remodeled, never been used when we moved in . . . and in all those passing years, the lime scale buildup + soap residue got pretty bad.
I tried everything. I mean EVERYTHING - from natural cleaners to harsh chemicals to the "leave it on and forget it" types, even tried using cleaners that weren't specific to showers. Or bathrooms. Some of the bathroom cleaners loosened the soap residue into a thick sticky mess that was virtually impossible to clean off not only the walls but whatever I was using to clean the walls - sponge, scrubbie, scrubbing brush, etc. Beyond that, all I've really been able to do is etch and discolor the walls with the harsh cleaners. The shower might have been "surface clean" but it certainly wasn't "down to the original surface" clean. I even scoured the Internet for ideas, and sadly found that everyone pretty much said lime scale with soap residue just could not be cleaned off effectively or safely.
I really hated my shower.
Now, when I wash my son's diapers, I use vinegar for the hard water and we also boil vinegar in our electric teapot to remove the lime scale. I know that citrus essential oils break down oil; I use citrus essential oils in my Citrus Scrub Soap. Not only does the Citrus Scrub Soap easily cut through the oily kitchen grease and grime, it will also take permanent marker off of plastic and remove adhesive.
So there I was thinking, there has to be a way to combine the vinegar with the citrus oils in such a way that it can stay on the walls to soak for an extended period of time. It's pretty difficult to soak vertical surfaces with runny liquids! Any thickener I added needed to be washed off easily and not interfere with the cleaning process. Eventually . . . eventually I got the bright idea to thicken the mixture with xanthan gum. Xanthan gum also acts as an emulsifier, keeping the essential oils dispersed within the vinegar. Xanthan gum clumps when added to liquid, but over several hours will thicken the mixture into something gooey and sticky, yet it can be washed off with just hot water. Xanthan gum can be found in grocery stores. It's expensive, but since such a tiny amount is needed, it will last a very long time!
I was so excited by the idea I made some right away. As I mentioned above, the xanthan gum clumps and doesn't mix well. No worries, stir it as best you can and let it sit for a few hours to thicken, stirring occasionally. How many hours? Overnight is good. I used my first batch within 3 - 4 hours, and 24 hours later, it was a little thicker. I applied it directly to the worst of the soap residue spots (make sure the shower walls are dry, so water doesn't dilute it), and left it on for at least 12 hours. And that spot came CLEAN. I mean, down to the original surface clean!! I was beyond excited about this . . . this meant that I *might actually* have a really clean shower again! I applied the rest of the mixture to the rest of the shower walls. It got thin in some spots since I had made a small batch. Then let it sit overnight and scrubbed it off in the morning. The applied mixture does dry on the shower walls, and you'll need warm, if not hot, water to loosen up the dried sticky mixture. But when you scrub it off, it takes the soap residue with it!
Some of my heavy lime scale spots were still there, and after repeated applications, were STILL there. Sigh . . . . okay, what now? Then I turned to citric acid - it's supposed to be better at breaking down lime scale. I experimented with the amount to add to my vinegar/essential oils/xanthan gum mix. I found that if I used a lot of it, it did a great job on the lime scale but it didn't rinse clean and left LOTS of white streaks on my shower walls, which is one of the issues I'd had with commercial cleaners that promised to cut through lime scale.
I also wanted to be able to cut through the soap residue a little faster, so for the next round I used most of the same essential oils I use in my Citrus Scrub Soap. Ahhh, not only did that smell fantastic, it really worked!! Citric acid and essential oils can be purchased online. I get a lot of my supplies at Wholesale Supplies Plus - if you order over $40, your shipping is free! (They have such a great selection of items it's not hard to spend $40!!)
Now back to the white streak problem . . . baking soda! A nice, natural, gently-abrasive scrubber. I had tried making a simple cleaner of just vinegar and baking soda years ago, but it didn't do anything for the soap residue, and couldn't stay on the walls long enough to break down the heavy lime scale. I tried adding it to the gooey mixture, but of course, baking soda reacts with vinegar - which yes, that is what I want, but not while storing it! What to do? Aha! Just dump a good amount in the coated dried tub, dip a wet scrub brush in it, and get to scrubbing.
Then for the real test: I waited. I let the shower get really dirty. Soap residue, lime scale buildup . . . it wasn't pretty and I really didn't want to take a shower in it! When I couldn't stand it anymore, I made a fresh batch of shower cleaner, applied it, and let it sit overnight. In the morning, I dumped a good amount of baking soda in the tub, ran a little hot water to wet down the scrub brush, dipped the scrub brush in the baking soda, and scrubbed away. It did take some scrubbing effort since I purposely let it get that bad, but when I was done, I had a sparkling clean, down to the original surface, CLEAN shower.
And it's all natural. And my shower smells fantastic. *Blissful sigh*
ALL NATURAL SHOWER CLEANER RECIPE
Container with a tight-fitting lid
1 c distilled white vinegar
1 tsp citric acid
1/4 tsp xanthan gum
No more than 10 ml (1/3 oz) combined essential oils:
sweet orange essential oil
tangerine essential oil
lemon essential oil
grapefruit essential oil
Directions: Mix the citric acid with the xanthan gum. Add vinegar and essential oils. Cover tightly - make sure the lid seals tight! Shake well to mix. Let sit several hours to thicken.
Once mixture is thickened, apply to DRY shower walls with a sponge, maybe a paintbrush, or I've even used my hands. Wait several hours (overnight is easiest). Then the next time you take a shower, dump some baking soda in the tub and scrub away!
This does rinse away best if you have one of those handheld sprayer shower heads, so you can do a final rinse/scrub to make sure all the baking soda grit is rinsed away.
(Please note you should probably wear gloves to apply the mixture to shower walls if you have any broken skin or are sensitive to citrus essential oils or citric acid.)
UPDATE 11/20/16 - I have been using this recipe to clean my shower since writing the original post, but mostly just use sweet orange essential oil instead of the EO blend because it's simpler when I'm in a hurry. As I recently found out - this recipe is excellent at removing gum from clothing, and works well at cleaning the gum-coated dryer, too. For the clothes, I sprayed it on, let it soak in a few minutes, used a bristle brush to scrub, rinse, and right back in the wash it all went. The dryer: first I sprayed on the shower cleaner and let it soak awhile. Then a little sweet orange essential oil cleaned the mess right off. Lastly, I finished up with a 50/50 vinegar/water mix to wipe up the essential oil residue and leave the inside of the dryer sparkling clean.