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The red bricks are really porous anyway. If you put a new one in a bucket of water, it will bubble for ages.
If they are pointed with lime, it isn't a problem and I wouldn't put anything on them.
@hoefla
You need to be 100% sure they don't sneak in some cement into that mortar. It's common for builders to do that, as it makes the mortar set faster but you just end up with a cement mortar with loads of lime in it.Lime mortar is either NHL and sand or lime putty and sand. Lime putty mortar doesn't have as much frost resistance as NHL mortar and isn't as strong. If you're in London, you'll be ok with a putty mortar, but out of town you want a hydraulic (NHL) lime mortar.
Aunt_Maud-
Regarding the brick porosity, this was regarding the enrtire house and not just the red bricks which have been cut back. My understanding was that they'll be more likely to get frost damage once the skin has been cut back. You can see the bubbles/holes appear as you start to cut back buff bricks. If the scaffold is up at the time, then I think it makes sense to add a coat of water sealant.
rodabod
I think your bricks will look fine once they’re done. Those soft red ones often crumble to bits and have to be replaced.
By the way, once you’ve had the skin of your bricks cut back like that (as they are on my house too) they should be coated in Thomson’s Weatherseal or similar as it makes them porous.