Need Help w Caulk Paint Question

[phrog]

Short as possible - I recently replaced part of the door sill on my mother's house. I glued a dowel backer rod between the sill and the underlying brick because the gap was about a half inch and very deep. The next day I added silicone caulk, waited a day, added caulk, waited a another day and added a third batch. After this, I waited another 24 hours and then I used exterior primer over the caulk, waited a day and added a second coat. I did the same with two exterior topcoats. Looked great for about a month and then this happened. (See the photo.) Looks like the wood or the caulk shrank (or both) breaking the paint at the top in some places and pulling from the brick beneath in other places. Have no idea what I did wrong or how to redo. Any suggestions would be appreciated.
Richard

[Charlie]

Deleted by me.

[phrog]

Thanks Charlie for the answer. I did clean it with an old toothbrush and vac and it was paintable caulk.
Richard

[cabinetman]

That picture isn't too clear to see exactly what happened. Silicone caulk doesn't take paint too well. I would try for a better wood repair leaving a minimal gap if any. I would use Polyseamseal Adhesive caulk if caulk is to be used.

If painted, you could use Bondo, or even a two part epoxy as a filler.
.

[just started]

I would yank the caulk out and refill with layers of body filler no more than 1/4" thick each, and then file and sand to match the surrounding contour and paint.

[mpauly]

If you have to use caulk, use acrylic....takes paint much better.

[pecker]

I have always primed, caulked, then top coated. Assuming you start with bare wood, alkyd primer, then acrylic or latex topcoat and water soluble caulk like Polyseamseal mentioned earlier.

That has always worked for me.

[phrog]

Thanks to all who answered this post. Will try to find the caulk mentioned and try again.
Richard

[phrog]

That picture isn't too clear to see exactly what happened. Silicone caulk doesn't take paint too well. I would try for a better wood repair leaving a minimal gap if any. I would use Polyseamseal Adhesive caulk if caulk is to be used.

If painted, you could use Bondo, or even a two part epoxy as a filler.
.

You're correct that the photo isn't too clear and I apologize for not posting a better one. The camera I was using isn't capable of getting real close without distortion. In the days of film cameras, I would've used a Macro lens and bellows but I've retired most of my good equipment since film is getting harder to find and processing (since I've sold most of my darkroom equipment) is expensive. I do appreciate your answer and will look for the caulk you mentioned. Again, thanks.
Richard

[phrog]

I would yank the caulk out and refill with layers of body filler no more than 1/4" thick each, and then file and sand to match the surrounding contour and paint.

Thanks for the suggestion. I actually considered this in the beginning but decided against it because the filler would abut very rough bricks and I thought it would be difficult to sand the filler satisfactorily without removing several layers (read ouch) of skin. The photo was insufficient to show this complication but I do appreciate your suggestion.
Richard

[jking]

If there's a gap between the sill & the brick, backer rod really isn't the right answer. You need to fill the gap with wood or something that will support the edge of the sill. It sounds like the front edge of the sill is flexing & causing the caulk to fail. The bondo mentioned would work fine. For a half inch gap, you might consider ripping a strip of PT to insert in the gap.

I'm also going to be a voice of dissent on the caulk. I do not like acrylic latex caulk. I prefer to use either polyurethane or paintable silicone. Both stay flexible & adhere better than latex. I have had acrylic latex pull away from brick within two years. The only paintable silicone caulk I've seen is GE Silicone II XST. It is a different product than their regular Silicone II.

I too have had better luck when priming the bare wood before applying caulk. If you're priming bare wood, make sure it is clean. Hit it with some sandpaper if necessary. I generally use oil based primer on bare wood, but, alkyd is also good. I haven't had good experiences using latex primer on bare wood.

[jking]

Thanks for the suggestion. I actually considered this in the beginning but decided against it because the filler would abut very rough bricks and I thought it would be difficult to sand the filler satisfactorily without removing several layers (read ouch) of skin. The photo was insufficient to show this complication but I do appreciate your suggestion.
Richard

It isn't as bad as it may seem. I've used the bondo type filler to do exactly what you're looking except mine was a window sill. The bondo is easy to work with & as long as you use some care, the sanding isn't bad. I think I laid down a piece of masking tape on top of the brick (you could use a piece of cardboard, too) to make a straight edge. The filler sands very well, I used a power sander, but, you could use a block of wood with a nice sharp corner to do the sanding. You'd be hard pressed to find which sill I repaired this way, it turned out very good.

[phrog]

If there's a gap between the sill & the brick, backer rod really isn't the right answer. You need to fill the gap with wood or something that will support the edge of the sill. It sounds like the front edge of the sill is flexing & causing the caulk to fail. The bondo mentioned would work fine. For a half inch gap, you might consider ripping a strip of PT to insert in the gap.

I'm also going to be a voice of dissent on the caulk. I do not like acrylic latex caulk. I prefer to use either polyurethane or paintable silicone. Both stay flexible & adhere better than latex. I have had acrylic latex pull away from brick within two years. The only paintable silicone caulk I've seen is GE Silicone II XST. It is a different product than their regular Silicone II.

I too have had better luck when priming the bare wood before applying caulk. If you're priming bare wood, make sure it is clean. Hit it with some sandpaper if necessary. I generally use oil based primer on bare wood, but, alkyd is also good. I haven't had good experiences using latex primer on bare wood.

What you said about the sill flexing makes sense. I hadn't thought of that because I was so sure that it was failure of the caulk. But you could be correct. I'll look into that before proceeding with caulk. But boy do I hate the thought of sanding that Bondo against the brick. Again, thanks.
Richard

[Tom Slick]

What specific caulk did you use?

[phrog]

What specific caulk did you use?

Sorry Tom, I just now saw your post. I got it at Lowes (or was it HD?). It is DAP Acrylic Latex Caulk Plus Silicone. It says it is good for "Indoor/outdoor; Mold and Mildew Resistant; Waterproof; Paintable; Permanently Flexible; and Easy Clean-Up."
Richard