The problem is that to get the look of chalk, you have to use something that applies at least close to the same, and nothing that would be waterfast or similarly durable is going to apply the same. Like pastels, they’re basically in between chalk and crayon in the way they transfer to a surface, but you can tell at a glance that it isn’t the same effect. The livers lines look more structured, fill in the valleys of something like cement or concrete more than chalk. And asphalt isn’t much different.

So you have a few choices. First is to go with chalk and a fixative. If you’re going for something artistic, that’s your best choice. It won’t last forever, but it’ll look like chalk while it lasts.

Second is to use grease markers. They’ll still smear, but should last through rain at least. It won’t look like chalk, but it’ll still have a similar enough vibe to maybe carry it off. You’ll have a limited palette unless you make your own, but you can get similar effects with something like cray-pas. It’ll be expensive as fuck though with pastels and such, that stuff isn’t meant for big projects.

Then there’s temporary marking paints. Like the guys that mark power lines use. Won’t last forever, but it’ll take some wear before flaking off the surface. They won’t look like chalk at all, but if you’re doing something more like hopscotch lines, it’d be a better pick imo.

It really comes down to your project. Like, I used to do fairly frequent sidewalk art on my own sidewalks with neighborhood kids. They’d do their thing, I’d do something a bit more complex. There’s sidewalk chalks that will hold up being walked on lightly for a few days as long as it doesn’t rain. Better than your typical chalk you’d use on paper or a chalkboard at least. Crayola was actually pretty reliable in that regard, but the colors were all primary or pastel; so you’d have to pick up anything else as regular artist’s chalk, which is a thing at most hobby and art supply stores.

But if I wanted a section to last longer for some reason, I’d usually make my own parafin or beeswax blocks. A little cheap pigment (like tempera powder as one example), some heat and molds, you have a slightly crumbly chunk of color that won’t get rinsed away in the first rain. It’ll melt and make a mess in the summer though, so you won’t want it where you’ll walk on it much.

Tempera paint actually does decent for very temporary but more wear resistant sidewalk art. Once dry, people can walk over it a little without it being wrecked. Rain makes it run though.

Damn, I just realized I miss the fuck out of those days. Come home from work, and there’s a gang of kids waiting. Break out the boxes of chalk, and everyone is just making happy pictures all over the porch, the sidewalk, even the street if there were other adults to run interference with traffic. There usually were, but not always. Rule was that if there weren’t two adults that could manage traffic, the street was off limits.

Since it kinda turned into a thing, there were days when not only my house, but houses all up and down the street would have suns and houses and stick figures under trees all over the driveways and such.

Anyway, old man memories aside, it depends on what you’re doing.

If it has to be water resistant, why using chalk instead of paint? Real question, not trying to make fun.

You could try covering it with hairspray. That’s what we used to keep our charcoals from getting everywhere in art school.

It should eventually wash away, but might help some.

Why? The whole point of chalk art is temporary. How are you going to clean the non water soluable substance you use? Chemicals? More permanent stuff is called paint, but it better be on your private property. The city does not want to immortalize your child’s brilliant art display.

Krylon makes “marking spray chalk” that is temporary and takes anywhere from a few days to a couple weeks to fade. It’s what we used to paint the train tracks on our parking lot for a kiddie train at our fall festival event.

Crayons?

I would love to know as well.

I would use it on Rand Paul and Mitch McConnell’s driveways.

Use normal chalk and then cover it with that water repellent spray?

Paint.

ikea chalk does last the longest form my testing

Something like this? It’s the “chalk” pens that are used on restaurant chalkboards for outdoor use. Wipe off-able, but rain proof.

https://www.amazon.com/Chef-Master-Rain-Proof-Markers-Pack/dp/B001CR6V12/