What wood filler do you use?

[GibsonGM]

I have a long sill on my farmer's porch. It was pretty roachey, so after prep I blooped it, slow oil primed, and stained it. It will get a topcoat of satin latex.

In a few spots, it has those 'fissures' that develop over eons in the sun and water makes them wider (say 1/8" to 1/4" in the worst spots). As a painter, our first instinct would be to caulk them before topcoating.
This is standard "painter practice".

However, I do know that over time nothing can last, and water WILL get under the caulk, lift the edges, maybe make things worse, and at minimum will require someone to remove it next time it's scraped and painted.

I've used generic 'exterior wood filler' a few times; no clue if it holds up (I think it's actualy Elmer's!). I've also used Minwax wood filler (binary, has a hardener with it...wood bondo), and believe that to be better.

What have been others' experiences? Would you think that 'water putty' is better than the above? Glazing compound? I don't think I'm in Abatron territory, but I would like to learn about the best way to deal with this, both at home and professionally...

[heartwood]

bingo, glazing putty!! blop, oil prime, apply putty and smooth with a putty knife dipped in thinner/turps...make sure to get the putty in just the fissures, don't 'frost' the entire sill...putty doesn't sand well so you want to make sure the putty is smoothed over...apply latex or oil finish paint directly over the putty...the putty I am referring to is sarco type m...if you can't get it locally, I can send you a small amount n/c...
send me a pm....
...jade

[GibsonGM]

Thanks, Jade! I thought that might be it...I glaze, and find that when the putty is 'done', it almost self-releases...sort of tells you it's time to repaint. I come across this on old homes I repaint and thought that was probably what they had used. And no damage beneath...

I've already applied a solid color stain (Arborcoat); hope that won't interfere

[Kashka-Kat]

Im unclear about what the"fissures" are - is this cracks in the wood itself or joints between pieces. If the former I would definitely use Abatron and just be done with it - all I can say is repairs Ive done on my exterior wood using this product (liquid + fill) have held up well over 10 yrs now, still holding paint and have not recracked.

The Minwax wood hardener product is not epoxy and way inferior to Abatron, imho - I say that based on experience of redoing same repairs numerous times before finally catching on that it just doesnt work very well.

I also liked to use an inexpensive Elmers wood fill for my more minor applications - it was tan in color and buttery smooth, it sanded smooth, didnt shrink, and held very well. But I just cant find this in big box anymore - there is just this stuff with a gritty texture that is horrible. Does anyone know where to find the old stuff with smooth consistency.

[1918ColonialRevival]

It all depends on the application. For something exterior that's going to be in the weather, I like the Abatron two-part products better than anything. The only downside is, they're expensive, but you get what you pay for.

If the surface is going to be painted and money is tight, you can also use Bondo or similar auto body filler. I've used this on exterior plywood before and it seems to be durable enough for the application.

[phil]

Interesting thread. Ive been pondering the same questions. The fir stairs I built a couple years ago have had a couple winters in full rain and there are some boards with cracks that run with the grain I want to fill before renewing the finish.

some of the risers had knot holes and I put a couple wood screws in at an angle in such a way that they dont' sit proud of the surface but the heads are in the knot hole and then filled with car bondo. using the red catalyst made the bondo a pretty good match. maybe the wood bondo can expand and contract better.

I dont' know if i can get sarco here.

when the cracks exceed 1/8th or so. I'd cut tapered strips. still use the filler , but anythign over 1/8th or so you can plug with wood and still use filler. you can fill the gaps part way , then drive the strips in, then finish the filling and replace the missing wood with wood but use the filler to make it so they dont' have to fit with precision. It just makes it so you don't have like 1/4" gaps filled with putty.

for example, fill the 1/4 gap with a roughly fitted 1/8th tapered strip and then you only have 1/16" of putty on either side.

the cracks aren't' always perfect or vertical but if you just cut some strips about 1" with one side about 1/16 and the other side about 1/8" then you can use that up as you go. plane off anything that sticks up.

I have some epoxy and use it for some things but I dont' think it expands and contracts like wood nor does it take any finish other than paint well. I think it's ok for small gaps if they are clean but maybe the sarco being softer, it might work better as any gaps are inevitably not perfectly clean inside and any dirt wont' help adhesion. I think epoxy is ok if you crack a board and still want to use it , in that case you can glue it back because it's clean and a good fit. It's a good waterproof glue but it isnt' really a gap filler although epoxy will bridge a poor fit a lot better than your average wood glue.

in fiberglassing usually polyester resin is used. epoxy is used for repairs to fiberglass. it has a higher strength. polyester is cheaper and stiffer. epoxy is more flexible but since it isn't porous it doesn't really expand and contract just like wood. neither do. so if you can use wood for most of the fill I think that helps. the epoxy is a stronger glue better adhesion. I wouldn't use either on stuff that is painted, except maybe the cracks which are new and dont' have paint in them.

bondo is polyester not epoxy.

you can also add wood dust or chips to epoxy to make your own filler or you can get the putty sticks where you chop a bit off and kneed it into a filler with the consistency of silly putty. It's good for some things but a bit expensive for cracks on stairs. there are lots of brands. Ive tried the one called PC woody it comes in white or brown in a couple of film cans so you can mix equal parts. it's ok for little repairs.

with this project since you have topcoated already I'd stay away from bondo, epoxy or polyester. It wont' adhere to the coating you have down already. those things will stick to clean wood but not dirt or paint.

[heartwood]

is the arborcoat oil or latex? I think it will work with latex but you know the rule of thumb--latex over oil but not oil over latex...if the stain is an oil penetrating stain, you may have an issue staining over the putty...the solvents weaken the putty...

in the past I used abatron for rot repairs...I now make wood repairs--i'm a professional so I have the time and expertise and get paid to do a good job...many of my fellow restorers have shared stories of moisture becoming trapped beneath abatron repairs and causing further damage that cannot be seen until the rot is quite significant...I do think that abatron is a very good product and far superior to minwax or bondo (nooooooo!)...many people, like kashka kat, have had good long lasting repairs with abatron...

...jade

[GibsonGM]

Uh oh, I may be stuck with caulk, then. Wah. The Aborcoat is latex Yes, oil on water, bad juju.

I've seen actual Bondo repairs 2 years later...oh man....the horror...!

Yes, the yellow filler from Elmer's is what I had mentioned. It actually works! But for how long, nobody knows...

I think I'll have to use this area for experimenting I'll take a pic later, so's we all can see what I mean.

[phil]

another way to approach it is with a router and straight bit. nail or clamp down a guide strip parallel to your crack. router along the strip enlarging and cleaning out the crack. then insert a strip of wood. You could use a 1/4" router bit or a smaller spiral bit , or even a circular saw and just make the strips the width of the sawcut that way you won't have any cracks showing and if you go 1/4" deep , good enough. if you want it more invisible you cut your strips on a very slight taper so they fit tight near the surface where it shows. I'd use epoxy to glue the strip in. or a waterproof glue. that way you are gluing to fresh wood. if you match the wood type and grain it can be pretty invisible. on stairs you might need to finish the cut with a chisel if the router can't get close to the end. If they are open stairs that might not be an issue. I sometimes use a laminate trimmer for things like that as it is physically smaller but it's just a router.
That's not as fast as just calking so it depends how fussy you want to get with it. It wont' take long once you get set up. if it's a clear finish at least you hide the gap with wood instead of putty. if you want o get real fancy you can set in 1/4 by 1/4 brass instead of wood or you can use hardwood as an accent. I thought it might be neat on stairs to set in some strips like that only a tiny bit proud of the surface for foot grip and to protect them from sliding snow shovels.

[GibsonGM]

That's a great technique, Phil, but this is both outdoors on a porch windowsill, and also there are like 25 cracks...you know, from the sun and having been neglected. Can't go to that level, LOL! But I would do what you suggest for an indoor issue, definitely.

Probably would use the Elmer's wood filler, which I've used before with good results. No negatives on my latex stain and so on. Caulk leaves too much of a 'dip', I really don't like that.