Do I absolutely have to remove old caulk before applying new?

For best results always start with a clean and solid substrate.

I would. Just get a good razor scraper and it won’t take you long to cut out the old caulk.

(please be in social…please be in social…please be in social…aw, nuts!)

You don’t “absolutely” have to remove the old caulk, but it will look and work much better if you do. Old caulk will be the first to begin to mildew, crack, or peel.

Filmfan is right. (And I a good social story too.)

I agree. If you go over it you’ll be happy in the short run, but irritated in the long run! A razor scraper works wonders on old caulk. And you might be amazed that when you cut a chunk off another chunk may just fall off with it!

Hold the phone for a quick second. Pics would be helpful but in a case where the old is very thin and not coming loose or separating and you are clever with the caulking gun you may be able to get by overlaying the old. I say may. Sometimes you can create much more damage to drywall and the paint job scratching off old caulk, especially if it is real silicone- that stuff will not come peaceably. I say this having done it, many times. If it is hanging loose and you can grab the end and pull it out then that would be the way to go. It’s going to depend a lot on how the first guy applied it. Either way if you are messy with a caulking gun, (there is a trick to making a pretty seam), it’s going to show, big time.

Sounds gross, but to smooth out any rough spots in newly applied caulk use spit on your finger to lightly tool the area. For some reason caulk doesn’t stick to spit and you will only be able to do a small stretch of seam with spit finger before it starts to stick. So use more spit to keep going,be real sure to wipe your finger clean between spit applications or you will experience a bitter taste, work quickly.

Yes, you do have to remove the old, or else the new won’t be new, it will be cover-over, with all the defects of the old.

Yes.

To answer your question another way, you don’t “absolutely” have to remove old caulk.

But if you want to do the job correctly, one time, and have it work – and last – then you should.

OK, OK, I will remove the old caulk. I could see how in most cases, this is the correct thing to do. But I was trying to figure out, in places where the old caulk is just a very thin band and somewhat recessed, if you could just as well first make sure it is clean and then lay a thicker band of caulk over it.

New caulk sticks to old caulk just as well as virgin surfaces as long as the old is still solid, or light enough to cover over without looking like a giant caterpillar. It depends if you want to make a career out of the work or just get it done already.

If you can remove the old caulk, you should. It usually could come off dry. However, you might want to wet it to try to pull it off and then let it dry before you re-caulk or you might have a mess.