Painting - Perfecting caulk technique

Hi,

I have done quite a bit of caulking but I'm prepping some new trim. Caulking between trim and wall is fairly easy because there is usually a pretty good gap and if it's not a perfect job it dosn't really matter since walls are usually textured. However, I need to caulk a lot of inside 90 deg corners (i.e. casing to jamb, jamb to jamb) with only a hairline crack. The difficulty with these is getting just enough to hide the crack but still maintain a crisp 90 deg corner.

Usually on these I would just use my finger and try to apply as little caulk as possible/necessary and come back with a damp towel to remove the excess that squeezes out from my finger. I never really touch the actual caulk line with the towel because in my experience it mucks things up more than it helps. I have also never really tried any caulk tools as I have heard nothing really works better than your finger.

I also wanted to ask about cracks that were so small that the primer filled them. I sprayed Zinnser oil based primer and some of the joints that are not attached with glue or fasteners filled with paint. I'll be topcoating with Ben Moore alkyd SI. My concern is the possibility of cracks appearing later. I suppose it's mostly a question of how much wood movement occurs. This should not be much of a concern since the trim is MDF but I wanted to get others take on this. I think this is one area where latex has oil based beat. A few cracks might be inevitable but if all of the joints cracked I would have a lot of egg on my face.

Thanks

The neater you apply the caulk, the easier it is to tool. IMO the best 'tool' is always your finger :D I prefer to use a damp sponge [a wore out sanding sponge backside works great] but a rag also works well.

Paint never really fills a crack! although it may hide it. Often tight cracks are the hardest to get a long lasting caulk job on because there is less surface area for the caulk to adhere to.

New construction always has high humidity so it is best to caulk every joint. Remodel work isn't as bad - usually HVAC in use and a lesser amount of "wet" materials.

I usually don't worry about keeping the crisp sharp edge between the casing and jamb. While I don't fill the angle with caulk, a little extra caulk usually means a more succesfull job - it's also a little quicker ;) The main thing is to neatly smooth out the caulk so it isn't noticable after painting.

On new trim it is common to caulk all corners no matter how tight the trim might be. I use a half filled 5 gallon bucket of water and a very smooth rag. Like Marksr said the tip of your caulk should be cut as small as possible for this work. too small you can deal with. too big is a mess and time consuming to clean. I would caulk everything on this new trim.

Thanks for the replies but I'm still not clear on what you are using the towels or sponge for. Are you using these to smooth the joints or just for cleanup near the caulk line?

Thanks

I like to put the sponge between my finger and the caulk. If you do a LOT of caulking you can rub a hole in your finger :eek: The sponge both protects your finger and if you lightly wipe it over the caulk it will smooth it out with out removing an excessive amount of the caulk.