Stone Chimney is Spalling

I’m in a new-to-me house, and noticed the other day that my chimney is spalling. It’s made from natural stone and appears to be some type of sandstone. It’s porus. I didn’t give it much thought when we bought the house last fall. We’re having a new chimney liner and cap installed this fall, so I was up there checking things out when I noticed the spalling.

Google investigations tell me I should be sealing my chimney every couple years to prevent this from happening.

1 Most advice on the internets is specific to brick chimneys. Obviously I need to seal it, but does the same advice for a brick chimney apply to natural stone or are there extra considerations that I need to take?

2 Looking for a product recommendations for a sealer.

As always, thanks for the help.

You want a sealer specifically made for stone.

Lowes carries one, I’m sure the other big box stores do as well.

https://www.lowes.com/pd/miracle-sealants-511-impregnator-32-fl-oz-clear-natural-stone-sealer-and-finish-pour-bottle/1000566003?cm_mmc=shp-_-c-_-prd-_-flr-_-google-_-lia-_-230-_-groutmortarandsealers-_-1000566003-_-0&store_code=2736&gclsrc=aw.ds&&gclid=CjwKCAjwnMTqBRAzEiwAEF3ndk31sww552VFOyenl7Ka7JLIX5HwDSkGNs4drXpLEmbVdnGSHHomQhoC4zMQAvD_BwE

I had that same problem, pieces on the roof and leaking. There is a fellow had a ad in the local newspaper, chimney repair. He removed the 4 inch concrete cap. replaced the bricks down to the roof, made a new cement cap. It wasn’t cheap or simple job. It was worth getting a professional chimney guy. That job is not for amatures.