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  1. #1
    Join Date
    Oct 2008
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    Default Cleaning Caulk off of Cast Iron Tub

    Folks,
    I took advice and got DAP KWIK SEAL for my fiberglass surround-cast iron tub re-caulk project. I am having trouble getting accumulated latex and silicone caulk off of the cast iron tub. Any suggestions? I have mineral spirits and denatured (and rubbing) alcohol. I was thinking of scraping some off with a razor blade (the heavier accumulations), but am worried this will scratch the tub.

    Advice would be appreciated. THANKS, and have a great holiday!

  2. #2
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    Default Re: Cleaning Caulk off of Cast Iron Tub

    Get yourself a paint scra-per that uses single edged razor blades and always work with a sharp blade. You'll be able to carve off the excess pretty easily.

    You should know that silicone caulk leaves behind a residue that nothing, including new silicone will stick to. You might be able to lay in a nice bead, but it won't last for long.

    Someone posted a means of removing the residue but you'll have to do a search for it as I can't recall what it was now. Paint thinner isn't going to cut it, neither will alcohol, although if you go back with silicone, alcohol works great to keep the silicone from sticking where you don't want it.

    Another thing that I've found works great to remove the bulk of silicone is a white solid rubber dog chew toy. The toy will act like an eraser and roll the silicone right out of there. You'll still be left with a residue to deal with, so thoroughly cleaning will still be an issue.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  3. #3
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    Default Re: Cleaning Caulk off of Cast Iron Tub

    cougars,

    Follow Spruce's idea of rubbing off as much as possible. make sure it's completely dry before you apply the new caulking. Let dry for a day.

    As far as how long the new caulking is going to last, it depends on things like contact with water, ventilation, mold build up, etc. And when you need to remove it, it will come off quicker than silicone.

  4. #4
    Join Date
    Oct 2008
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    116

    Default Re: Cleaning Caulk off of Cast Iron Tub

    So a straight blade razor "scr-aper" won't mar the enamel on the cast iron tub?
    Thanks.

  5. #5
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    Default Re: Cleaning Caulk off of Cast Iron Tub

    Quote Originally Posted by Cougars1996 View Post
    So a straight blade razor "scr-aper" won't mar the enamel on the cast iron tub?
    Thanks.
    If you work slowly and patiently with a single edge, you won't damage the cast iron tub. For the plexi, use even more caution and you'll be all right.

  6. #6
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    Aug 2007
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    Default Re: Cleaning Caulk off of Cast Iron Tub

    Quote Originally Posted by Cougars1996 View Post
    So a straight blade razor "scr-aper" won't mar the enamel on the cast iron tub?
    Thanks.
    That is correct, and I hyphenated scr-aper because this site censors the "r" through "e".
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  7. #7
    Join Date
    Oct 2008
    Posts
    116

    Default Re: Cleaning Caulk off of Cast Iron Tub

    Sadly, I am back. I cleaned as best I could, caulked with DAP KWIK SEAL (latex) and let it dry for 48 hours plus.

    It seems like the caulk never fully cured and has curled up. When I wipe it off, when the bulk of it gets wet it dissolves.

    I guess I am going back to silicone. Any additional suggestions? Does anyone have experience with those caulk strips sold at the big box stores?

    Thanks for the help.

    John.
    Last edited by Cougars1996; 12-27-2011 at 06:51 PM.

  8. #8
    Join Date
    Aug 2007
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    6,481

    Default Re: Cleaning Caulk off of Cast Iron Tub

    Don't use those caulk strips, they give you a false sense of security.

    If you must go back with silicone, then do yourself a favor and get a spray bottle of rubbing alcohol.

    Cut the tip of the caulking tube at a 45* angle and keep the hole as small as possible, yet still apply the caulk you need. A hole diameter of about 1/8th inch is usually sufficient.

    Prime the caulking gun so that it's ready to push caulk the moment you start pulling the trigger. Start in a corner press the trigger until it just starts to squeeze out around the tip of the tube, then start dragging it along the joint. You want your rate of travel and pressure on the trigger to be balanced so that you don't get excess goobers all over the place. If you have to stop and clean the tip, do so, and absolutely clean the tip between applications.

    Once you lay a nice uniform bead, spritz the top of it with the alcohol, then lay it off 2" at a time with your finger, wiping between each stroke. When you've finished the first layoff, go back and make a second layoff in a single stroke.

    The alcohol will keep the silicone from sticking to things it shouldn't when you lay it off. Wiping your finger frequently keeps you from making a mess.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  9. #9
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    Default Re: Cleaning Caulk off of Cast Iron Tub

    I've been using DAP for over 35 years and it has never failed me. The secret is in your right index finger (or left).

    Applying caulking takes practice, so don't give up.

  10. #10
    Join Date
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    Default Re: Cleaning Caulk off of Cast Iron Tub

    Try vinegar to remove left-behind silicone residue. Vinegar (acetic acid) is the solvent used to keep it liquid in the tube.

    Any caulk you use needs to be left for several days without moisture contact to cure.

    As for a razor blade, hold it at a very close angle to surface. The steeper the angle the more likely it is to scratch.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

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