Reducing a tomato based sauce?

[FatBettyintheCoop]

I've got a glut of cherry tomatoes so I've been making basic tomato sauces, chutney, soup, etc.
I want to try making ketchup but the recipes I've seen say to simmer and reduce the sauce by half but if I leave the lid off the saucepan it's going to spatter everywhere isn't it? If I leave the lid on with a tiny gap, will the water still evaporate?
Also, if you've got any good recipes for using up cherry tomatoes, please let me know.

You could try putting a sieve over the top of the pan to catch the splatters. Just leaving a tiny gap would work eventually but would take much longer.

A splatter guard?

Just keep the heat really low and have the lid off.

Just use the biggest pan you own and keep the heat low.

I use a big stock pot and a diffuser on the lowest heat/smallest ring on my gas hob and no lid. I also find that adding a bit of water helps it to break down better and really reduce (obviously takes a bit longer but it really works).