I usually just cut the lines by hand with a smaller angled brush and hope for the best, wash the rest

We have had somewhat better luck with FROGTAPE brand painters tape. But there is an art to applying it. -TAKE YOUR TIME. Don't rush. -after the tape is applied, run a ruler over it to seal the edge. -Paint all the coats you intend, THEN TAKE THE TAPE OFF! DO NOT WAIT! Slowly pull the tape at a 30-90 degree angle. The longer you wait, the more the danger of peeling the paint with the tape.

I just put a long, straight piece of cardboard under the wood, paint, move the cardboard down the baseboard, then paint that section and so on. Tape is for amateurs

I painted professionally for several years. We didn't tape straight edges like this - we learned how to paint to a hard line directly. Once you are skilled, it's faster and doesn't suffer from the problems you're having. Cleaning up the occasional oops manually turns out to be much faster.

Also make sure that floor is clean before applying tape. If it's dirty or dusty you don't get good adhesion.

So I went through this exercise years ago, I installed lots of trim in my house and painted with colors so cutting in would be very time consuming and stressful. In fact with base or chair rail its nearly impossible to cut in when painting wall after trim - I had a pro tell me in this case they paint the wall first, then chair rail, then wall under chair rail then base (top to bottom method). The problem with painters tape is that its designed primarily for easy releease so its made from crepe paper - thus no chance of blocking seepage.

There are tapes made from smooth almost plastic like backing at the home centers (Scotch). The one I used is also blue and I just looked it up, seems they may have changed the name from what I have, now they call it sharp lines. This will make a huge difference as long as the surface you are taping to is perfectly clean and not too textured.

I tried the Frog tape once and spent hours applying it and next morning it had all fallen off, I think the adhesion is really low.

Take a magazine. Rip all the pages out. Slide the pages under your baseboard for the entire length. You can take the extra step of taping them together if you're real bad at painting so they don't slide around. Pull out the pages as soon as you're done and throw them directly in the bin.

A good brush, well cared for and quite familiar to the painter, is the way I go every time.

If tape is loose, and paint gets near, it will wick under the tape.

Removing tape may mess up wet paint.

Have you tried running a ramp rag over the painters tape before painting? It helps make clean, crisp lines on walls.

Wedge sheet metal between the floor and baseboard

My father used to do similar with an old piece of linoleum. More rigid and doesn't soak anything up. I think a wide putty or taping knife could also work.

i think the tape is for protecting against an accidental brush stroke, not for creating a full liquid tight seal. if you drown it in paint it will fail. so just use the tape as "training wheels" for cutting in neatly in the first instance :)

This. I use cheap plastic cutting mats from the dollar tree. Hold up a little better than cardboard when used repeatedly.

Professional painters have a loop on their pants to hold a wet rag, to wipe anything as they go. I have suggested these type paint guides to friends, just wipe it as you move along the baseboard/ floor if it gets messy. You can also put down some News paper or a drop cloth if your nervous. https://www.lowes.com/pd/Warner-12-in-Plastic-Paint-Guide/1000024777

If you can't learn to cut a line, do this:

Tape.

Paint along the edge of the tape lightly with the SAME COLOR THE TAPE IS PROTECTING.

Now paint with the other color.

No bleed through.

Paint the baseboards after you cut to size but before you install. Then just touch up the nail gun holes.

If REpainting, tape of course and use good painter tape. And do the bottom bit against the floor with a hand brush and not a lot on the brush. With the rest, again don’t put too much paint on the brush. Avoid drips

I tape, then add just the very thinnest line of caulk along the tape edge (using a finger or a rag to make it nearly invisible). Paint, then remove the tape - no seepage, and a nice clean line.

You are using too much paint

Giant puffy knife on the ground you can paint against and move along with the brush as you go

I hate the tape. I paint by hand with a tiny brush, even an artist's brush, if I have to, and just have a steady hand. Also follow with a damp good quality paper towel. Near carpet, use thin cardboard undere baseboard or quarter round. Slow and steady wins the race.

I use a 24" paint shield and a good brush.

‘Paint’ the tape with plain water about 10 minutes before you paint. Causes the frog tape to creat a seal. Peal tape off before paint dries.

Don’t load the brush with paint and jam it in the tape!!! Use a small brush. Dip in paint and “scrap off” all the excess paint several times. Then gently brush the top of the baseboard working you way to the tape with VERY LITTLE paint on the brush!!! Work to not touch the tape.

OOOOHHHH! Really? Thank you! Sounds like a great tip!

Frog tape. It uses a special gel formula that stops paint

Removing tape may also mess up dry paint. There is no winning

And that tape is expensive and can’t be reused.

Don’t tape. Use a square brush not an angled brush. You’ll need a bit of practise but a good clean square brush applied with light pressure to flatten the bristles, starting from top or mid point and slide along until you get to the bottom will yield a straight clean cut. Use a moisten rag to clean anything that hits the floor while it’s still wet.

THIS IS THE WAY. I paint professionally. We tape all trim except the tops and bottoms of windows/ doors where you cant see. We then use white or clear AlexFlex caulk and lay down the thinnest bead possible on the edge of the tape. Then, wipe off most of the caulk or spread it out as thinly as possible. Paint the masked area immediately, and remove the tape immediately after painting to reveal a crisp cut line with no bleeding.

I’ve done it two ways-

1. Paint the base before you install it, go back and caulk and touch up the holes.

2. Put paper down, install base- then paint. Pull paper.

Both work fine.