Recaulking At Previously Silicone-caulked Shower Door Frame - Kitchen & Bath Remodeling - Page 3 - DIY Chatroom Home Improvement Forum

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Old 03-13-2012, 09:20 AM   #31
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Old 09-12-2012, 11:23 AM   #32
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How to remove silicone from fiberglass

I did a search on the title for this post and got some answers that did point in helpful directions. Ultimately I tried using charcoal lighter fluid at my son's suggestion - a great substitute for Goof Off. I put a little on a paper towel and wiped the old silicone with the towel. Then I started to work off the remaining silicone with a plastic putty knife my fingernail and the paper towel with lighter fluid. The lighter fluid definitely helped remove the silicone. Waiting a few minutes after wiping with the fluid seems to help too. I was able to get all noticeable silicone removed. Then I did a final wipe down with rubbing alcohol. The result was a smooth, shiny clean surface.
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Old 01-02-2013, 10:51 PM   #33
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You saved may arse!

Originally Posted by Nestor_Kelebay View Post

This post is longer than 10,000 characters, so I had to split it into two posts

Recaulking bathtubs is probably one thing that perplexes more homeowners than any other job. One thing that people should realize is that silicone caulk can be difficult to remove if you don't know how to do it, and NOTHING sticks well to silicone caulk, not even silicone caulk.

It's because people don't know how to remove old silicone caulk COMPLETELY that their new silicone caulk doesn't stick well, and that results on garbage advice being given, like filling the bathtub with water before caulking, which is likely going to result in trying to caulk a wet joint which will yield predictable results. Garbage in, garbage out.

If you remove the old silicone caulk COMPLETELY, the new silicone caulk will stick to both tub and tile like chewing gum to the underside of a church pew.

This post is in 4 parts:
1. How to remove old Silicone caulk
2. What silicone caulk to buy
3. How to place new silicone caulk
4. How to clean mildewed silicone caulk

1. How to remove old silicone caulk:
The way to do this is to first remove as much as you can by mechanical means. This means scraping as much as you can off with a razor, or if you have a fiberglass or acrylic bathtub that may be damaged by a sharp razor, use a Tungsten Carbide paint scraper or a plastic windshield scraper or any other reasonably sharp but relatively soft material that won't damage your fiberglass or acrylic surfaces.

Next, apply a product called "Silicone-Be-Gone" which is made by DAP and can be found in the caulk aisle of most home centers. Silicone-Be-Gone is nothing more than gelled mineral spirits. If you can't locate Silicone-Be-Gone in your area, just buy some mineral spirits (or paint thinner or "solvent" or Varsol), get some strips of paper towel wet with the stuff, drape them over the silicone caulk and cover with Saran Wrap for an hour or two to prevent the paper towel strips from drying out.

Web page showing Silicone-Be-Gone:

Neither Silicone-Be-Gone nor mineral spirits will "dissolve" cured silicone, it will just make the silicone swell up and get much softer so that it can be more easily removed by mechanical means. After letting the Silicone-Be-Gone work for an hour or two, scrape the silicone caulk a second time and you should remove more silicone (that will accumulate on your razor blade or scraper). Apply more Silicone-Be-Gone and spread it with your finger this time so that the warmth softens the gel and you apply a thinner coat.

After leaving that Silicone-Be-Gone sit for another hour or two, scrub the area with a green or white Scotchbrite pad (or the kind sold in grocery stores for scouring pots). The difference between the green and white pads is that the green pads have an abrasive mixed into the plastic before drawing that plastic into a fiber. The white ones are pure nylon fiber which doesn't contain any abrasives. I use the green pads on my enamel steel bathtubs, but I'd probably use a white pad on fiberglass or acrylic tubs to avoid scratching the fiberglass or acrylic material.

After scrubbing with the Scotchbrite pad, clean the Silicone-Be-Gone off with clean water and dry with a cloth or paper towel. If you're using paint thinner, I'd use Simple Green to clean the paint thinner off first, and then rinse the area with clean water. There should be little silicone left, but any that is left will prevent the new silicone caulk from sticking at that spot, so we need a way to confirm that there is ABSOLUTLEY NO residual silicone caulk remaining.

Remember that the Silicone-Be-Gone makes the silicone caulk swell up and get soft. Get a small quantity (a photographic container full is plenty for one bathtub) of a very fine powder (like Portland Cement, drywall joint compound, or probably even normal baking flour would work). Use a small brush to apply that to the area where the silicone caulk was, and then rub the powder with your finger.

If there is any residual silicone caulk remaining, the fine powder will become embedded in it, thereby revealing it's location. If there is no residual silicone caulk, the powder will be wiped cleanly off the tub by your finger.

Mark the spots where the sticking of the powder reveals the existance of silicone caulk with masking tape or something, and redo just those areas again with the Silicone-Be-Gone. You should find that the residual silicone caulk is so soft now that it can be removed even by scraping the surface with a popsicle stick sharpened in a belt sander (or a plastic windshield scraper). Then, check those areas again with the fine powder.
Once the powder doesn't stick anywhere, let the area dry and start putting the new caulk on. Maybe wipe down the area where the silicone caulk was with mineral spirits (paint thinner) and allow to dry. It will evaporate completely without leaving a residue, so there's no need to clean again.

2. What Silicone caulk to buy:
Silicone caulks come in different price ranges. The more expensive caulks will contain more mildewcide, which means that the caulk will be more resistant to attack by mildew. I personally have found that Dow Corning's "786" silicone caulk is better in that respect than DAP "Titanium II" silicone caulk. If you're buying GE silicone caulk, pay a bit more and get their "1700" silicone caulk instead of their regular "Tub & Tile Silicone Caulk". Not only will these caulks be more mildew resistant, they will stick better and cure to a stronger rubber than the regular silicone caulks.

However, in the last section of this post, you'll find out how to clean mildew off of silicone caulk, so you can keep any silicone caulk clean, not just the better ones.

3. How to place the new silicone caulk:

Use masking tape (1/2 or 3/4 inch wide) to mask off the joint you're wanting to caulk. Use 3/4 or even 1 inch wide masking tape if you have little experience caulking. Put the edge of the tape about 1/4 inch away from the joint on both sides of the joint. That means stopping the tape about 1/4 inch from any vertical joints you want to caulk as well. This can be done by gripping a single edge razor blade in a pair of needle nose style locking pliers. Put the tape in place and then put the edge of the razor firmly on the masking tape, and then pull the tape at an angle so that it tears off at the razor's edge.

(If you do a lot of caulking, you can probably just caulk the tub freehand without even bothering with masking tape, but I'm writing this up for new homeowners who want to get a good looking job without the caulking experience to do it freehand.)

Before putting the new silicone in place, press down the edges of the masking tape so that you're sure that the new silicone won't get under it.

Squeeze out the new caulk onto the joint and wipe it down with a dry finger so that it's relatively uniform in thickness all along the joint. Don't let so much caulk accumulate on your finger that it starts getting on the tub or tile on the OTHER side of the masking tape. At this stage, you simply want a relatively uniform amount of caulk all along the joint, and how you accomplish that really doesn't matter.

Once you've got the new silicone caulk reasonably uniformly distributed along the joint, pull the masking tape off.

Give the new silicone caulk a few minutes to "skin over". This is a good time to mix up a 50/50 solution of liquid dish washing detergent and water.
You have no idea how this information saved my butt! I had redone our bathroom - in a house we rent - and needed to remove the silicone caulk. I used old eye shadow and found all the spots I was missing. I had already wasted 3 days caulking - not knowing silicone caulk had been used. I had to start from the beginning and I followed your advice. Thank you sir!
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Old 01-02-2013, 11:58 PM   #34
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I bought a tube of silicon calk once. I made one hell of a mess Acrylic for me now. Bottom line its for the professional.
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Old 02-02-2014, 02:29 PM   #35
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Originally Posted by Nestor_Kelebay View Post

4. How to clean mildewed silicone:

Mix up some baking soda with straight bleach to make a paste that you can spread with a tea spoon (even a plastic tea spoon). (I use a small oval painting spatula that you can buy in art supply stores for painting with thick "paste" style paints that come in tubes.)

Use a putty knife to scoop the bleach/baking soda paste out of the mixing container and hold it near the silicone caulk. Scrape the paste onto the silicone caulk and spread it with the teaspoon.

Cut Saran Wrap (or any clear food wrap that will stick to tub and tile) into 4 to 6 inch wide (or so) strips and put them over the paste so it doesn't dry out, and leave it overnight like that. My experience is that it won't do any harm to ceramic wall tiles or enameled steel tubs to leave it for several days like that.

When you pull the Saran Wrap off and remove the paste, your silicone caulk will be white as Manitoba snow. And, you can do this repeatedly to the same caulk to maintain it in a mildew free condition.

You'll find when you're doing this that the baking soda settles out of the bleach so that it'll be necessary to continually mix the paste up before scooping some out. If you're doing a vertical or joint on a ceiling, you CAN mix Vim Thick Bleach (made by Unilever Canada 1-800-896-9286) which is just gelled bleach with talcum powder to make a paste that sticks well (and behaves all the world like joint compound). (Adding baking powder to gelled bleach results in the gelled bleach becoming ungelled so that you ruin it.) However, since Vim Thick Bleach only has a sodium hypochlorite content of about 3.5 percent, it's not as effective at killing mildew than regular bleach which is 6.25 percent NaOCl.

I save the old paste and reuse it. Just add some more bleach and mix it up, and it's ready to be used again. I think talcum powder is less dense than baking soda, so I'm going to try making paste from talcum powder and regular bleach when I run out of paste made from baking soda to use.

Hope this helps.
I was browsing around to check some stuff out and I came across this post. I know it's not a big deal but I coudn't let it go without saying something. Bleach does not kill mold or mildew. Sorry. It only bleaches it. Period. It's an old myth perpetuated by the fact that it's no longer black. Even when all the color has been bleached out of the mold, it's still present. 100% as it was before you bleached it. Mold doesn't react with sodium hypochlorite. It looks as if it does but it doesn't.
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Old 02-09-2014, 01:20 PM   #36
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Originally Posted by buddiiee View Post
I was browsing around to check some stuff out and I came across this post. I know it's not a big deal but I coudn't let it go without saying something. Bleach does not kill mold or mildew. Sorry. It only bleaches it. Period. It's an old myth perpetuated by the fact that it's no longer black. Even when all the color has been bleached out of the mold, it's still present. 100% as it was before you bleached it. Mold doesn't react with sodium hypochlorite. It looks as if it does but it doesn't.

That's was interesting information - thanks for sharing.

I looked online due to your post and found that biocide is the best was to really kill mold. Where would the average homeowner pick up biocide? Is it an OTC product?

I don't have a big problem with mold but would like to be effective when I run into it. Also, do the cleaners that claim they kill mold actually work like the Lysol bathroom cleaner? Perhaps they have ingredients in addition to bleach?

I assume that biocides will also kill algae?

Appreciate your input.
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Old 02-24-2016, 02:01 PM   #37
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I mixed a batch of the baking soda and bleach. Applied on the black mold, covered with saran overnight, and washed the next day. Worked like a charm! I have clear caulk and colored tiles, and NO DISCOLORATION from the mixture!! Thanks!!
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Old 06-05-2017, 05:19 PM   #38
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Re: Recaulking at previously silicone-caulked shower door frame

Nestor_Kelebay: A thousand thanks for your posts. I now feel I'm on my way to re-caulking my tub for the last time. My philosophy is: "Take the time to do any home repair in such a way that you'll never have to waste the time to re-do it" and, at my age (67) I can hope to achieve my goal most of the time. But, until now, I've been a miserable failure in the caulking department and I finally understand why. Thank you SO much. I'm on my way to my local hardware store to get the magic potion and I've copied and saved your wonderful explanation so I can score points with friends and family members.
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