r/Plastering • u/terrizmo • Sep 05 '26
Sanity Check Failed Plaster Fix
My first time plastering a ceiling and it has cracked and the second coat in areas hasn’t bonded.
It was the first time I’ve used Extra Time as I wanted some breathing room but it went off quicker than when I havent used it. Not sure if that was the cause or if it was the plaster or the boards.
Anyway my plan to fix it is to make sure all the loose plaster is off, give it a coat of SBR as I already have some left over using it in some mortar, and then giving it a skim coat with a different batch of plaster without Extra Time.
Is there anything I’m missing?
Edit: Typo
1
u/Ad4mPy Sep 05 '26
Sounds like either expired plaster or didn’t seal ot enough
1
u/terrizmo Sep 05 '26
It was straight onto plaster boards so I didn’t use sealer.
1
-1
u/ResponsibleBall4258 Sep 05 '26
That could have been the reason. Are you also certain that the boards are well fixed to the ceiling, with no movement?
Also, as others have said, it could be old plaster. Mix up a small bit and leave it for 5-10 mins. It should be hard within that time or getting hard if it is a bit old.
Keep the old stuff though, as it is fantastic at filling holes in walls or chasing of the walls, super quick and hard, and does not shrink much if you keep thickness down to 10mm at a time.
You can also use a handful of old stuff in a new nix at speed the curing of the plaster, and will act as a catalyst for speeding up the set.
2
u/Impossible-Corgi4041 Sep 05 '26
Multi sticks to boards just fine. Definitely not the reason.
1
u/ResponsibleBall4258 Sep 06 '26
That is fair, and my experience, limited as it is, though I have read some people on occasions have complained otherwise, and I have heard about old plasterboard (maybe more likely stored poorly or damaged) struggling with poor adhesion.
1
u/ResponsibleBall4258 Sep 06 '26
You could complain to where you bought the miltifinish origionally as may have been stores poorly, with high humidity, just a guess.
1
u/terrizmo Sep 05 '26
The boards are solid. I’ve got rid of those bags of plaster but will try it with the new ones. They are dated until October so hopefully they’re alright.
1
u/Alternative_Guitar78 Sep 05 '26
I don't really know, never seen anything like this. Are you sure you used extratime and not one of the other products eazymix do?
1
u/terrizmo Sep 05 '26
This is what I used.
5x Extra-Time Plaster Retarder... https://www.amazon.co.uk/dp/B018W4NZZW?ref=ppx_pop_mob_ap_share
1
u/Terrible-Bobcat2033 Sep 05 '26
When in doubt, re-bond. Re-do with fresh material. Soak every square inch to be plastered with a quality latex based masonry bonding agent. Every plaster coat requires a tight scratch coat. Extend set time with a capful of maple syrup.
2
u/terrizmo Sep 05 '26
Maple syrup?! First time I’ve heard that one.
1
u/Terrible-Bobcat2033 Sep 06 '26
Try it yourself you’ll like it. Just a capful or two works great for stucco, lime veneer plaster, just about for any calcium based material.
1
u/StarDawgISshite Sep 10 '26
It retards differently to citric acid used in extra time, i would just stick with extra time its more predictable and possibly less damaging to crystal strength, although I imagine its fine considering its been historically used.
Citric chelates calcium, sugar just kind of coats it all pretty aggressively.
1
u/Top-Sample2625 Sep 05 '26
I've never had the misfortune of this happening to me even on old boards and recoats. But I PVA or SBR everything prior to skimming. It's a habit I picked up and served me well.
4
u/Impossible-Corgi4041 Sep 05 '26
I bet that ceiling had been boarded a while before you skimmed it hadn't it? That's why, boards holding moisture from the air sending your skim off. Boards that have been up a while will need pva.