PC-Woody window repair

Continued from our last episode where I was standing around scratching my head trying to figure out what to use to fill the rotted corner of that window sash.

Just finished filling it with PC-Woody. I ended up making a form out of scrap wood: one L-shaped piece for the window stop profile (more or less), another L-shaped piece of plywood for the sash front surface, and two pieces for the bottom and side. Covered all casting surfaces with waxed paper. Drilled holes in the rotted members, put in 1/4" threaded rod and joined them with an L-bracket and nuts.

The PC-Woody stuff seems OK. However, I must point out to those who might go this route that the stuff is a little hard to use. If you get it nice and warm like they suggest (~80° F), it makes it easy to mix. The problem is that the mixed stuff has the consistency of thick peanut butter, and it's not easy to smooth out the surface (try doing that with a gob of peanut butter sometime): it pulls and sticks, so you can't just screed it flat. So I gobbed it on pretty thick, planning on rasping and sanding it down when set (will wait a couple days for it to cure hard).

But I'm positive the repair will be solid, probably as good as the wood that was there before.

I ended up with the PC-Woody after looking at several other similar products at a couple of local building supply stores. The other ones were in kits, with a sealer included in the box (I bought the PC-Woody sealer separately and used it). The thing about these other products is that they were pretty expen$ive, in the neighborhood of $40-50 a kit. PC-Woody is a lot cheaper: I got the 12 oz. size (2-6 oz. cans) for about $10 each. Only needed one of those, plus what was left over from my little 4 oz. cans to fill the gap (pretty big hole).

I'll report later after I finish up the repair.

Reply to
David Nebenzahl
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I appreciate your desire to minimzie cost....I tried to do the same thing YEARS ago using Bondo vs WoodEpox / LiquidWood from Abatron.

The Bondo failed miserably on the repair of exterior redwood window sills.

I switched to Abatron products & never had another problem. Yeah, they're not cheap but they work & never fail.

btw the Abatron stuff has a real world shelf life of YEARS. I used product that was 19 years old and it still kicked & cured hard

WoodEpox has a every workable consistency, can be shaped will putty knives & will hold shape until cured.

cheers Bob

Reply to
fftt

On 9/6/2009 7:00 PM fftt spake thus:

I'm curious how exactly it failed. I noticed some wood repair putty made by Bondo when I was shopping around.

Reply to
David Nebenzahl

The main way wood patch compounds fail is that over time the wood expands and contracts, and if the patch isn't either flexible or matched to wood's expansion rate, the bond between them will break. Bondo, for example, is very stiff and doesn't match wood's expansion rate.

Cheers, Wayne

Reply to
Wayne Whitney

Interesing, I have used body filer type bondo and the woodfiller bondo for exteranal wood repairs and both worked well. You can control how hard the bondo gets by the amount of hardener you use. I admit to using a small amout so that I have more working time and this leaves it more pliable.

Jimmie

Reply to
JIMMIE

I've seen stuff that you inject with a needle/syringe to harden up rotten wood, I think it was relabeled super glue. No you can't build up missing material with it, but it gives the old wood a lot more strength, and can be used where the damage isn't so bad.

Reply to
Tony

Tony wrote: ...

All the products of that type I've looked at (and that's been a number over the years of restoration :) ) are actually thinned epoxies rather than cyanoacrylate glues. The do have their uses; one usually needs both types of product if need one has been my experience.

Did lots of window sills and other similar finish work on antebellum restorations in the Lynchburg, VA, area years ago when these were new products. AFAIK those have held up well for the 30 years since we did them...

Reply to
dpb

My experiecne has been the same....redwood sills (south facing SoCal windows) repaired 22 years ago are still good. Of course they need maintenance along the way (just sand & paint to keep paint film intact)

Bondo (at least in 1987) was not ok for use on exterioe redwood, per discussin with Bondo tech people.

Yes, Bondo's final stiffness can be adjusted via amount of hardener used but I would never again risk its use outdoors on redwood.

The WoodEpox system is more expensive but the cost of failure is MUCH higher comparatively.

cheers Bob

Reply to
fftt

On 9/7/2009 9:32 AM dpb spake thus:

The sealer I used (also a PC product called "wood hardener") was strange: water-based, seemed like thinned acrylic something or other. Definitely not epoxy. I used it. Hope it works ...

Reply to
David Nebenzahl

Oh, that...yes, I've used it too; wasn't what I was thinking of, sorry.

It is an acrylic in a urethane polymer--sorta' a very, very thin glue.

I've had some successes, some "not so much" with it depending on the application. If you can get it absorbed well in sufficient amount and to a sufficient depth, it will do it's thing. It doesn't seem to work well w/ SYP, much better w/ softer pines and other woods I've tried it with.

--

Reply to
dpb

On 9/6/2009 6:51 PM David Nebenzahl spake thus:

Well, the repair is pretty much done. Took the window over today to test-fit it. All that remains is priming, filling, glazing and painting.

Couple things:

o One problem I ran into was voids due to air bubbles. Seems difficult or impossible to avoid if one doesn't have a gigantic vacuum chamber; they're a result of mixing. I mixed the goop *very* thoroughly, so probably ended up beating in lots of air. But the voids should be easy to fill; I'm priming them first, then plan on using painter's putty.

o The putty is very easy to work after setting. I ended up taking the bulk of it down with a hand plane, followed by an orbital sander.

o There was a small low spot, but on the outside of the sash, so I'm not going to sweat it. Point is, it's probably better to use what seems like too much goop, rather than risk low spots.

I have every confidence that this repair will last a good long time. And I see no need to overspend by buying the more expensive epoxy products. Epoxy is pretty much epoxy in this application.

Reply to
David Nebenzahl

Bondo works best when the damaged wood is properly hardened. I would think this to be true for any wood filler product.

Jimmie

Reply to
JIMMIE

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