How Many Days To Spray Internal Non-Hydraulic Lime Skim Coat?

[aockenden]

Hey all,

How many days do you typically keep spraying your internal skim coats (specifically non-hydraulic lime based). The background suction is insane on my son's bedroom wall that we skim plastered 2 days ago, probably because it's got 5 CM thick of bone-dry insulating lime plaster backing coat behind it, and it's trying to turn white on me almost as fast as I can keep spraying it. I did wet the wall down thoroughly before we skimmed it but I guess it needed a couple rounds of spraying leading up to the time we skimmed it. Lesson learned for next time.

I'm spraying it down every day first thing in the morning and last thing in the evening, and sometimes in the middle of the day as well. I'm just wondering how long I should keep this up before letting it dry out and calling it good.

Thanks.

 

[Kearn]

I’d go about a week rule of thumb… but…?!? I’ve been caught out recently with various finishes which I thought were stable, only to find cracking further down the track!

 

[HMOman]

good advice 1-2 weeks

 

[aockenden]

I’d go about a week rule of thumb… but…?!? I’ve been caught out recently with various finishes which I thought were stable, only to find cracking further down the track!

And you think if you’d have sprayed longer then that cracking wouldn’t have occurred?

 

[aockenden]

good advice 1-2 weeks

Ok fine I’ll keep going then

 

[Kearn]

And you think if you’d have sprayed longer then that cracking wouldn’t have occurred?

Can’t say for sure - the stuff on wood wool panels, yes as there’s no suction. However, I also have some incredibly thirsty bricks which were heavily pre wetted, but still cracked - I’m not sure surface spraying here longer would’ve helped much in the grand scheme! I was also spraying and trowelling / wet sponging to close up gaps.

I’ll add, these instances were all 8mm coat going on in one pass. Obviously a genuine thin top coat is much less susceptible to the substrate, so misting will help but also has no real aggregate to hold it together and resist cracking. most of my top coats were safe after a few days as they were only a few mm. Although a number of these went straight on green to hemp lime, so had moisture from within.

It’s all very variable…! Compression during application also plays a part…

 

[aockenden]

Can’t say for sure - the stuff on wood wool panels, yes as there’s no suction. However, I also have some incredibly thirsty bricks which were heavily pre wetted, but still cracked - I’m not sure surface spraying here longer would’ve helped much in the grand scheme! I was also spraying and trowelling / wet sponging to close up gaps.

I’ll add, these instances were all 8mm coat going on in one pass. Obviously a genuine thin top coat is much less susceptible to the substrate, so misting will help but also has no real aggregate to hold it together and resist cracking. most of my top coats were safe after a few days as they were only a few mm. Although a number of these went straight on green to hemp lime, so had moisture from within.

It’s all very variable…! Compression during application also plays a part…

yeah there's a ton of variables tbh. hard to come up with a solid formula isn't it?