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  1. #1
    Join Date
    Jun 2011
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    Default caulking sideboards

    Hi

    I live in Phoenix, AZ. The house has paneled siding and the joints are in need of caulking. With all the varieties of caulk types, I'm not sure which is the best to use. I'm thinking latex as I will be painting the house after the job is finished.

    Another question is when to apply the caulk. From now until about October daytime temps will be at or above 100 degrees. Mornings are in the 80s now and 90s in July and August.

    Should I get up early and work until 9am? Or would it just be better to wait until the temps break back into the 90s and apply the caulk then?

    Appreciate the advice.

    John

  2. #2
    Join Date
    Aug 2007
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    7,195

    Default Re: caulking sideboards

    For exterior work that will receive a lot of direct sunlight or expansion/contraction due to temp fluctuations, I would recommend a poly/beutyl type caulk.

    It's best to work in cooler temps so that the caulk doesn't skin over before you can get it applied and laid off. I would suggest mornings or later evenings when the temps are cooler, also, pay attention to how the caulk is responding to the heat. If it's skinning over quickly, then run shorter beads that you can get laid off and finished before skinning occurs.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  3. #3
    Join Date
    Dec 2010
    Location
    Houston Texas
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    2,969

    Default Re: caulking sideboards

    The surface temperature is critical for the next few hours after the caulk is applied as the caulk takes time to cure. Ambient air temps are irrelevant. We have the same problems in Houston. I recommend waiting until your 'winter' months to apply. Even 90 is too high imho. What do the caulk manufacturers say?

    Where were you fixin to apply the caulk? What type of siding materials do you have?

  4. #4
    Join Date
    Jun 2011
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    208

    Default Re: caulking sideboards

    John:

    There are some caulks that are exceptionally better in some applications than others. For example, silicone caulk can be used in very high temperature applications of 300 or 400 degrees F.

    But, for caulking siding, just about any caulk will do the job. Latex caulk has the advantage of being paintable.

    However, if you can find this caulk in your area, you should give it a try:



    Kop-R-Lastic is now made by the Henry Company in the USA. It's a synthetic rubber caulk that guns easily, tools well, sticks to just about everything and is paintable. But, the reason why I like it so much is that once it's fully cured, it becomes a very strong rubber. If you ever need to remove the caulk, you just get one end of it started, and it pulls out of the joint just like a rubber rope. When I tell people that, they presume that's because it doesn't stick well. In fact it sticks as well as any caulk needs to stick to last 50 years, but it has the advantage that it cures to a strong rubber, so that it'll pull off the surface it's stuck to before it breaks.

    I'd never use silicone caulk anywhere except in a bathroom. It works well, but the problem is that if it fails on you, you have to remove it completely before anything (even another silicone caulk) will stick to that same surface, and removing silicone caulk completely can be a real hassle. Since Kop-R-Lastic pulls off cleanly, you never have that problem with it.
    Last edited by Nestor; 06-18-2011 at 07:04 PM.

  5. #5
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
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    1,808

    Default Re: caulking sideboards

    Over the years, I have had very good results with either Vulkem of Sonneborne NP-1. Both are urethane caulks. They adhere tenaciously, are elastomeric and paintable. You should wait 24 hours before painting because they do shrink somewhat as they cure. Painting prematurely causes unsightly cracks in the paint film, although they do not impede the protection. Being urethanes, they cure faster in the presence of high humidity. Also, unlike latexes, you don't have to worry about what happens if a sudden rain storm occurs. The surface must be dry at the moment of application, but if it rains 30 seconds later, no damage will occur.

  6. #6
    Join Date
    Jun 2011
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    208

    Default Re: caulking sideboards

    Ordjen:

    I like Sikaflex 1a, which is the equivalent of NP1. For the longest time I couldn't find a good way to store partial tubes of the stuff, and I'd have to dish out another $7 every time I had a need to use the stuff.

    What I discovered is that if you candy cane a partial tube and immediately put it in the freezer, it'll keep for months (or longer) that way. I'm thinking that's both because the humidity of cold air is very low, but also because chemical reactions slow down significantly at lower temperatures.

    When you need to use it, just take the cold tube out of the freezer, and both apply some pressure with your gun and pull on the cured plug at the end of the nozzle, and the cured plug will pull out with fresh polyurethane caulk behind it. Then just give it time to warm up, and it's as good as a new tube.

    You can do exactly the same thing with Kop-R-Lastic.

    Johnpsyc:
    Sonneborn NP1 and Sikaflex 1a are both excellent caulks, and I wouldn't hesitate to recommend them for use on your siding either. I've never used Vulkem.



    Last edited by Nestor; 06-19-2011 at 12:21 AM.

  7. #7
    Join Date
    Mar 2008
    Location
    nova scotia, canada
    Posts
    1,522

    Default Re: caulking sideboards

    i prefere poly butyl caulking as well for exterior application. ive seen silicone fail more times than poly,

    the 3 types i use are "Flex 9000", "Flextra" both by mulco and then "Quad" by lepage.

    some people swear by "MONO" however water breaks it down which rendors it useless


    as for application and the correct conditions, as mentioned dont apply it in direct sunlight as it will skin over too quick to tool if needed, and dont apply it when the surface is wet from either cleaning the residue of old caulking off or just after it rained. it wont stick correclty
    fire up the saw and make some dust

  8. #8
    Join Date
    Aug 2007
    Posts
    7,195

    Default Re: caulking sideboards

    Quote Originally Posted by jkirk View Post
    i prefere poly butyl caulking as well for exterior application. ive seen silicone fail more times than poly,
    Silicone!?!?!?! What?!?!?! Bad boy!!! Bad BAD boy!!!!! No silicone, for anything, EVER!!!!

    You say you've seen silicone fail, I say I've never seen an instance where it's worked, and I won't even mention how many times I've seen silicone misused.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  9. #9
    Join Date
    Jun 2011
    Posts
    208

    Default Re: caulking sideboards

    The only place I use silicone caulk is around bathtubs and to seal the tail piece into a bathroom sink. I might be convinced to use it under the lip of a drop in kitchen sink, but otherwise I won't use it anywhere exept a bathroom. Never ever never use silicone caulk if you don't have to.

    Silicone is a double edge sword. It works well when it works, but it's like fighting with a bear to deal with it when it doesn't work.

    PS: You don't need to know the rest...
    (yeah, I'm gonna get in trouble over this one)


    The name "silicone" actually comes from the word "ketone".

    A ketone is anything with the chemical formula:

    A
    |
    C=O
    |
    B

    Where the "C" is a carbon atom and the "O" is an oxygen atom.

    If A and B are both methyl groups (-CH3), then that chemical is called dimethyl ketone, or acetone for short. Acetone is nail polish remover.

    If A is a methy group (-CH3) and B is an ethyl group (-CH2-CH3), then that chemical is called Methyl Ethyl Ketone, or MEK for short. Acetone and MEK are chemical cousins.

    (And, if you happen to be stoned on pot when reading this, if A is the ethyl group and B is the methyl group, it's still MEK.)

    Originally, chemists made plastics out of carbon, which forms 4 covalent bonds. Silicon also forms 4 covelent bonds, so chemists tried making the same kind of plastics out of silicon that they had previously made out of carbon.

    The very first silicon based plastic they made had the same number of oxygen atoms as silicon atoms, so they thought that plastic had a chemical formula similar to a ketone:

    A
    |
    Si=O
    |
    B

    And so they took the prefix "silic" out of the word "silicon" and the suffix "one" out of the word "ketone" and came up with the name "silicone" for this new silicon based rubber material.

    But, it turns out that silicone rubber doesn't have that structure at all. All silicon based plastics have the general formula:

    .....|
    .....O
    .....|
    A - Si- B
    .....|
    .....O
    .....|
    A - Si- B
    .....|
    .....O
    .....|
    .....etc.

    Where "Si" and "O" are silicon and oxygen atoms, respectively.

    Pardon the periods. This web page deletes spaces, and so periods are needed to get the structure right. In fact, ALL silicon based plastics have that same structure, it's just that the A and B groups are different in different kinds of silicon based plastics. By changing the A and B groups, you can make silicon based plastics that do everything from conduct electricity to prevent liquids from forming foams.

    The first silicon based plastic to be created was silicone rubber, and in that case A and B were both methyl (-CH3) groups, so that rubber was called "poly - dimethyl - siloxane", or PDMS for short. That word "siloxane" simply means a plastic with a silicon-oxygen back bone. Silicone rubbers are still used to make highly water resistant plastics. The best snorkling and scuba diving equipment is made out of silicone rubbers.

    And that's why there's a "Silicon" Vally in California, but you use "Silicone" caulk on your bathtub. Note that "e" on the end of the word "silicone" means that it's a silicon based plastic.

    Now, I'm sure someone's gonna bark at me for getting all chemical in here. But I find this stuff interesting, and I expect others do as well.

    Learn more than you need or want to know about silicon based plastics at Dow Corning's web site:

    http://www.dowcorning.com/content/di.../discoverchem/

    http://www.dowcorning.com/content/discover/?e=

    Last edited by Nestor; 06-19-2011 at 05:50 AM.

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