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Beth777 07-03-2008 08:33 AM

Need help with caulking problem and fuzzy wood!
House has older composite wood siding, old paint coming off. We are now prepping the house to repaint.

First question:

After friends came to help do prep work, we found that some of the silicone nail hole caulking was not properly wiped down. It has dried on with an area of bumpy caulking residue around each nail hole. If we paint over that, it's going to be pretty conspicuous.

What's the best way to remove excess dried-on silicone caulking?

Second question:

Areas of the composite wood siding have been weather-damaged. If those areas are scraped to remove peeling paint, we are left with a fuzzy sueded sort of damaged wood area. We have been told that his type of wood siding isn't sold anymore, so we can't replace with matching siding. Not positive about that information on availability of replacement boards.

What's the best way to repair the damaged composite wood surface so the final painted surface will appear smooth instead of "fuzzy"?

Please help!!!

slickshift 07-03-2008 09:48 PM

If your friends used silicone caulking to fill nail holes on a surface to be painted, the excess goop is the least of your worries

Exactly what did they use for caulk?

Beth777 07-03-2008 11:07 PM

It's Acrylic Latex Adhesive Caulk Plus Silicone
DAP Alex Plus

It says Paintable, and Easy Water Clean-Up.

Says it's okay to paint with oil-based or latex paints after it dries. That should be okay...I hope?

The easy clean-up they refer to would have been *before* the product dried rather than after!

We experimented with rubbing the spots down with a flat sanding pad. The stuff holds on tight, and it's rubbery-feeling. Kind of hard work to sand off the dried spots of goop, but maybe that's our only option now?

Nestor_Kelebay 07-04-2008 12:00 AM


I expect that caulk you bought was a "siliconized acrylic" caulk.

If the stuff is more acrylic than silicone, then acetone (which is frequently used as nail polish remover) should dissolve it. Try removing the problem caulk with nail polish remover, and if that works, you can buy acetone for about $12 per gallon at your local home center. (also be aware that acetone will dissolve latex paints, and at a slower rate, oil based paints). Xylene will dissolve latex paints quickly, but oil based paints very slowly if at all.

If the stuff is more silicone than acrylic, then look for a product called DAP "Silicone-Be-Gone" in the caulking aisle of your home center. It softens silicone so that it can be much more easily removed by mechanical means, such as scraping with a putty knife. My understanding is that "Silicone-Be-Gone" is nothing more than gelled mineral spirits, so if you can get most of the caulk off with a sharp scraper, then you should be able to remove the remaining film with ordinary paint thinner (aka: "mineral spirits" or "solvent" or "Varsol").

If you paint over that "fuzzy wood", does it look appreciably different than painting over the normal stuff?

PS: You can ignore the rest...

Did you know that silicone rubbers were first discovered when chemists tried to make the same kind of plastics with silicon as they were making with carbon? It's true. Both the carbon and silicon atoms have a valence of 4, which means that they form 4 covalent bonds. So, it was natural for chemists to see if they could use silicon instead of carbon to see if they could make plastics like polyethylene and polypropylene out of silicon instead of carbon.

Did you know that the word "silicone" comes from the fact that the very first silicone rubbers produced were believed to be polymers with monomers that had a structure similar to a "ketone". A ketone is anything with the structure:


where A and B can be anything. If both A and B are methyl groups, then it's "dimethyl ketone", or "acetone". If A is a methyl group and B is an ethyl group, then it's methyl ethyl ketone or MEK. And, if you're stoned, if A is an ethyl group and B is a methyl group, it's still MEK.

Anyhow, in naming the new rubber, they used the silic- from silicon and the -one from ketone to come up with "silicone".

But, silicone rubber turned out to have a Silicon-Oxygen backbone like this:


with other stuff bonded to every silicon and oxygen atom, so it wasn't similar to a ketone after all. Still, the name stuck, and that's why it's "Silicon Valley" or a "silicon" chip, but it's a "silicone" caulk. The final "e" in the spelling being due to not understanding what the stuff actually was.

Ya gotta know this stuff to get your DIY'er merit badge.

Beth777 07-04-2008 03:06 AM

Thanks for the science lesson!
Very interesting! I can see that it takes a lot of knowlege to earn a merit badge around here!

Yes...siliconized acrylic.

Will try the nail polish remover test first, to see what conclusions may be drawn from the results, and proceed accordingly. Thank you!

Painting over the fuzzy wood gives very rough results. It looks bad, and may tend to collect dirt and pollen faster than smoother wood.

I sanded some of it back and reprimed, with smooth, pretty results. The difference is significant enough that we are compelled to keep on sanding. It may seem like a sanding eternity out there before we're done...but it will be worth the effort.

Update: We have 1 1/2 sides of the house cleaned up, gently sanded smooth, and primed. We started with the worst and tallest side of the house, then rounded the corner to the 2nd-hardest side.

Pressin' on!

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