Cracks on Sealant

[ACH]

Help!

Prior to painting, I sealed all the corners, door frames and edges of my room with Polycell flexable sealant, left this to dry overnight, following morning put on a solvet based undercoat over the sealant (as recommended on other posts), and later that day started putting on Dulux Vinyl Matt.

The next morning I had all the hairline cracks over the sealant even though I had used the solvent undercoat!

Any advice- did I not leave the sealant long enough to cure? or Did I not leave the solvent undercoat long enough before the Vinyl Matt? Or both maybe. Or have I done the wrong thing completely?

A guy at the DIY store said I could use Dulux Trade Primer Sealer over the sealant now which maybe could solve the problem and hide the cracking, but I am not sure.

Grateful for any advice on where I went wrong and how I can solve this.

 

[confidentincompetent]

Hmmm.. I find the undercoat works ok. Though I do thin down the u/c with white spirit. and make sure not to apply too heavily and feather out to blend etc.. and of course make sure it's dry before applying matt emulsion. I'm guessing maybe the undercoat was applied to heavily (( ))) which in corners takes overnight to dry. In general I seal,wait an hour then prime with u/c, then as I had thinned and applied lightly, the matt emulson can go on in a couple of hours.
I would try a thinned u/c on one of the cracks and see if a coat of emulsion dries ok. I'm sure it will..


I dont use polycell myself though.
Good luck
John

 

[ACH]

Thanks for the reply and useful advice John.

Two more questions if I may;

Which oil based undercoat do you use?

Roughly what ratio do you thin your undercoat with white spirit?

thanks

 

[darren7]

I have always found the same, I have thinned it down, ( the undercoat) and even waited a week.... tiny hairline.

I have tried loads of brands of caulk, its the same..... but only with Dulux Trade V Matt.

every other paint is ok in the corners., Rich matt, silk...... all ok


Darren

 

[confidentincompetent]

I have always found the same, I have thinned it down, ( the undercoat) and even waited a week.... tiny hairline.

I have tried loads of brands of caulk, its the same..... but only with Dulux Trade V Matt.

every other paint is ok in the corners., Rich matt, silk...... all ok


Darren

Think it's because the dulux trade Matt is truly 'matt' and loses its tension on anything glossy, like sealant. I normally find the u/c thinned and applied lightly ok. Though if I'm using silk/softsheen I dont bother priming.

Another reason for cracks in corners can be the Matt emulsion is too thick and needs to be spread out. this is called 'Mud cracking'.