Will lime plaster react badly with gypsum?

[Minkeycat]

We've been told to patch some blown plaster in our house but to use lime plaster for the job even though the blown plaster is gypsum (or something like that - it was done in the 60s/70s and is "the wrong stuff"). I'm concerned that if it's just patched with lime plaster the two different types will react and there will be a visible line where they meet. Is this simply the wrong thing to do or are there products you can apply to the 'join' that will hide any staining. We've had this happen in a previous house but that was overseas and I don't know what types of plaster were used there as I wasn't around at the time it was done.
Thanks for any advice

 

[MikeG]

I would certainly patch like-for-like, or with something inert like Polyfilla if the patch is small enough. I'd love to know what the person who advised you thought there is to gain by using lime on a gypsum-plastered wall. Frankly, I can't think of a single benefit, and I can come up with a number of down-sides. I would also comment that patching plaster is rarely 100% successful, and that for a really good job you'd skim over the whole lot.

 

[a twig]

I've patched gypsum with hydraulic lime based plaster, no problems.

Join not visible and after a couple coats of clay paint, colour matches fine.

 

[livias]

Lime and gypsum do not react so there is no issue there. As others have said it is more of an issue of the continuity of finish. Like Mike i would tend to use gypsum again or just filler for small holes, unless you have to strip back a complete wall in which case do it properly with lime mortar

 

[MatthewC]

Lime and gypsum do not react so there is no issue there.

It's not so much a reaction but more likely the thermal effects due to the different coefficients of expansion - over time the two could separate. I saw that here where polyfilla had been used to patch a lime plastered wall - the polyfilla was just held in by the wallpaper (and came off with it)!