Is caulk sandable?

Caulk often is the best stuff, but you have to remember that it is not sandable. The trick is to get it right first time! It is water soluble, so you can smooth it with a damp sponge etc. The main attraction is that it is very easy to wipe into small imperfections, and it remains slightly flexible which is handy round door frames etc.

If you want something similar, but sandable, then look for one of the low density fine surface fillers. Toolstation do a "Instant Plaster Filler" that is a little like caulk in use, but can be sanded. Product code 87431.

The idea of caulk is that it shouldn't need sanding if correctly applied with a decent spreader. So saying all the ones I've tried shrink badly on drying and need three or so goes. But once you've achieved a good finish seem to last pretty well.

I have learned something new today again. i do love this NG, and appreciate you all taking the time to help me.

thanks

Yes; I sand first and wash down, and finally apply the caulk as above: no further sanding required. If it's still tacky: well, it's not gone off yet, however most types are overpaintable pretty quickly (ie, overnight not needed).

David

It goes almost hard eventually..several days/weeks

It doesn't actually - or at least not like a conventional filler. If you break the end off the tube weeks after last use it bends a fair way before breaking. So flexible it remains.

If you want something that is flexible, can be sanded and over painted then one of the modified silicone sealants such as Evostick Nail and Seal can be used to replace caulk. Unfortunately it is made in only one colour, white, so it's not a replacement for every sealant in every use but it is excellent where the limitation in colour/transparency is not an issue. It doesn't shrink in use which is also handy.

It's useful stuff to have available since it can be used as a replacement for gripfil and it can also be used for caulking.

replying to Steve Firth, Becky wrote: Please help me without making me feel more stupid than I already do. In prepping my wood stair treads for paint, I used paintable wood filler. But when I went back to sand, I saw that many places were still deeply gouged. So (gulp) I made a classic beginner's mistake: I realize now I screwed up by skimming paintable caulk over these areas.

Here we are two days later and my stair treads are still tacky to the touch in places. To make it even more horrifying, I am reading that caulk can't be sanded. I applied it/skimmed it pretty smooth but planned to sand it to perfection.

Now I read caulk not only can't be sanded, it shrinks over time. So basically my stair treads will look like sh** by next month. If the caulk even ever dries.

Is there any hope left? Please be gentle in your responses. I feel very stupid.

Why didn't you just use another layer of wood filler?

It is quite normal to fill, then sand, then fill any remaining low spots, then sand again.....

The main thing to remember is to do your final sanding with a fine sandpaper to avoid leaving gouges from coarse sandpaper.

Given that the caulk is still not set, I would be tempted to scrape it off, clean remainder off the filler, and then try a bit more filling and sanding.

Cheers

Dave R

Some types of caulk are sold as sandable, but even they don't sand very well. I think you need to scrape it off and do it again with filler or something.

Bill

If what you put in isn't setting, just take it out as best you can. If it's setting but very slowly, the remaining thin amount will then set far sooner.

Re filling generally, I go by the rule of never leaving a single grain above the finish level. That means it takes 2 or 3 goes, but zero sanding time. It's quicker & you don't end up with the problems that sanding sometimes causes.

NT