Compound for filling cracks in wooden quoins (corner blocks)?

[blueman]

Many of the wooden quoins (corner blocks) on our 1870's Italianate house have cracks and gaps in them.

I'm looking for a filler that would have the following properties: - Paintable - Sandable - Exterior grade - Able to withstand seasonal expansion/contraction cycles

Any suggestions?

I tried caulk, but it leaves a very messy result since it is not sandable and leaves a rough film

I tried woodfill but it doesn't seem to hold up to the expansion/contraction cycles

Thanks

[PDQ]

You probably used the wrong caulk .

For exterior fills such as you want use silicon caulk which is = paintable.

After you pump the caulk into the cracks wet your finger and smooth the = lumps down. If you apply the caulk with discretion you will not need a wet finger or = sanding.

Be sure to read the labels as there is silicon caulk which is not = paintable.

P D Q

[Max]

This stuff works great.

[Lew Hodgett]

If you want a crack filler for wood, then epoxy and micro-balloons.

If you need a caulk, talk to SikaFlex tech service in Detroit (800#) for an industrial version of 291 used in marine work.

Lew

[blueman]

Based on the description of "Scoop golf ball size amount of filler into plastic lid and squeeze in a thin 3/4 inch long line of hardener from the tube", this Minwax High Performance Wood Filler sounds similar to Bondo -- is it just a wood colored bondo or does it have properties better suited to wood repair?

Also, how does Minwax High Performance Wood Filler compare with epoxy products such as SystemThree Sculpwood or Abatron's WoodExpox?

Thanks

[blueman]

I find that silicon caulks look even more caulk-like than the latex-based caulks and that they are harder to work. And since they are not workable or sandable after hardening, I don't know how you can get a seamless repair. But maybe I am missing something here...

I really want something that will look and behave like wood so it will fully blend in.

[dadiOH]

You didn't mention how big these gaps and cracks are. Nor how old. Age is important because if the gaps/cracks are largish and old then the wood surface on the interior of the gaps/cracks has aged and weathered and may present an adhesion problem with whatever you put in.

You really have only three choices (and probably only two practical ones)...

1. Clean up the gaps/cracks and glue in wood splines or dutchmen with weather proof glue. Probably not practical but if you decide on doing it you need to have fresh wood to glue to and the way to do that is to cut partially thru the quoin with a saw or router, choice dependant on width of crack. Cut wide enough to have fresh wood on each side.
2. Caulk. True, it isn't all that sandable but it *is* sliceable. Handles expansion and contraction well too. This would be my first choice for smallish cracks - up to 1/8" or so. Caulk *can* be applied smoothly.
3. Resin with a filler. Two main choices of resin: polyester and epoxy. Multiple choices of filler: saw dust, silica (Cabosil), micro balloons, talc and more. Silica wouldn't be good, too rigid and hard to sand. Micro balloons make a fairly easy to sand putty as does talc. Bondo is polyester resin and talc.

The problem you may encounter with any resin/filler combo is wedging; i.e., expansion/contraction of the quoin against the rigid filler may either cause the crack to crack more or push out the filler a bit.

I used to have a good sized wooden sailboat and used both Bondo and proprietary filled epoxies to fill gouges and dings (never a crack though). Both did a decent job, couldn't see any diffrerence between them; after a year or two or three areas filled with either were a smidge proud and needed to be sanded down again. Neither ever "let loose". I think Bondo is under rated.

The only cracks I ever had were on a teak transom I put on. I fixed them with teak splines as explained above.

[Nova]

..which is just about all of them. Even the ones listed at "paintable" don't hold paint well.

"Q: The kid at the do-it-yourself megastore sold me 100% silicon caulk. He said I could paint it, but the paint just crawls off. Now what?

A: We have heard this one more times than you would believe. NOTHING will EVER make 100% silicon caulk paintable. Not primer, not time, not crying or praying. All you can do is scrape it all out, then re-caulk with a painter's silconIZED acrylic caulk. And hope you don't have to buy a new trim package."

[RicodJour]

You might consider replacing the compromised quoins (good usage by the way - almost everyone incorrectly calls them 'coins') with something like Azek or another expanded PVC product? The stuff holds paint wonderfully well and is very easy to work.

R

[blueman]

Good point. Given the age of the house and the fact that upkeep has been variable over the past 150 years, I would assume that most of the cracks are old and have weathered.

In terms of size. They vary in width from hairline to maybe 1/4" (or

3/8"), with most of the fillable ones being more like 1/16" to 1/8".

How would you compare the following resins: Bondo (cheap!) Miniwax High Performance Wood Filler SystemThree SculptWood Abatron WoodEpox

Thanks!

[Max]

Are the quoins painted or stained. Here's a sample of some patching I did.

[PDQ]

"paintable"=20

Interesting observation. =20

The only time I had silicon not take "paint" was when I tried to apply a = stain first - dumb move.

I found the caulk did not like stain but still took to acrylic paint. I = used the caulk to seal cracks between my windows and stone walls. =20

I have some caulking that is in need of replacement - it is almost 30 = years old and the paint is still on it. Only problem is time has = started to blacken the fills.

Who knows, maybe I was using painter's silconIZED acrylic caulk all = along.

P D Q

[J. Clarke]

You sure that you weren't using acrylic caulk with no silicone in sight all along?

[PDQ]

Not likely. I make a habit of only getting silicone as it gives me the = best results.

P D Q

[dadiOH]

I can't. The only one I've used is Bondo; actually, "automobile body filler" - Bondo is a trade name.

I suspect the Minwax one is Bondo revisted. The System Threee would be an epoxy with some type of filler, I know not what. Ditto the Abatron.

Just as a general thing, anything with epoxy will have better adhesion than one with polyester resin (Bondo). However, beaucoup tons of polyester have been used...both now and over the past 50+ years to repair/fabricate boats and fix dings in cars. Seems to last pretty well :)

[Max]

I've used Bondo and Minwax. Minwax is a better product for your application. It appears to me to be just an epoxy mixed with some sort of filler, possibly even wood dust. You add a hardener just like you would with regular epoxy. It sets pretty fast so it's not a good idea to mix a lot at once. It's paintable, sandable, water proof and easy to shape. The only reason I haven't used the other products mentioned is cost and availability. (Minwax is available at the Borg)

Max

[RicodJour]

messagenews: [e-mail]...

Silicone is a homeowner's caulk, far as I'm concerned. There's limited use for the stuff other than in bathrooms and for very limited uses on the outside (vinyl windows to vinyl siding - and I'd still prefer the alternative). People use silicone because that's what they're familiar with. Polyurethane and polysulfide caulks provide superior results as anyone who uses caulk in a marine environment can attest. They're also more expensive, but that's the, ahem, price you pay.

R

[PDQ]

messagenews: [e-mail]...

Must be you have one of those holes in the ocean into which one pours = money. :)

P D Q

[Lew Hodgett]

Strictly the bottom of ther bucket stuff.

Absolutely.

IMHO, for the small amount spent on caulking for a project, avoiding silicone is a no-brainer.

Lew

[Lew Hodgett]

You saiid it, also poor adhesion.

?

Takes the mystery out of mixing up fairing.

Pricey but convenient.

It will also get the job done.

?

HTH

Lew

Lew