horror

[dick turpin]

hello, can anyone tell me if pva has a shelf life????? i have just plasterd a 2 m area of wall and toooo my horror the plaster has cracked all over-looks like the salt lakes, the mix was good and conditions were good(not 2 hot) The pva may be about 3 tears old?????

cheers

[Dave]

.........

[dick turpin]

I take it the oops means the 3 year old pva may not be up 2 the job???

[smurf21]

take a look

PVA Glue Expiration? - Question of the Week | The Wood Whisperer Woodworking Video Podcast and Blog

[Dave]

Products have shelf life's and i think 3 years will be dead ...

[kilty55]

incidentaly i used an open bag of plaster to skim a ceiling last week,,im assuming moisture had got into the bag as it was stored in a damp shed open because it was fine when i put it on the hawk by the time i went to trowel it on the ceiling it had gone solid in the space of 20 seconds..weird

[dick turpin]

now you mention it kitty the bonding coat and the top coat r probly as old as the pva.......it did get stiff quick, i just thought i was out of practice....lucky its in my house, doh

[Ajax123]

Gypsum bonding and finish coat are made from Beta Hemi Hydrate Calcium Sulphate and has a shelf life of around 3 months. You were luck it weren't gone hard in the bag. The chemical reaction which forms gypsum chrystals when water is added is controlled by the addition of weak acid retarders (Usually Citric acid) this also has a shelf life so my guess is your PVA was dead, Your plaster dried out too quick and set too fast and shrank too much to hold itself together. My advice - scrape it off and start again with a new bag of finish. - all of £5.00 inc VAT

[diamondtiling]

incidentaly i used an open bag of plaster to skim a ceiling last week,,im assuming moisture had got into the bag as it was stored in a damp shed open because it was fine when i put it on the hawk by the time i went to trowel it on the ceiling it had gone solid in the space of 20 seconds..weird

An open bag in a damp shed? It would heve been sucking moisture in like a sponge

[doug boardley]

hello, can anyone tell me if pva has a shelf life????? i have just plasterd a 2 m area of wall and toooo my horror the plaster has cracked all over-looks like the salt lakes, the mix was good and conditions were good(not 2 hot) The pva may be about 3 tears old?????

cheers

out of interest, what was the substrate you plastered onto, and what type of plaster were you using?

[dick turpin]

on to brick work around my fire place, used thistle bond,will def remove and start again

[whitebeam]

Old pva, you could have applied the plaster on wet pva which would'nt hold it and can start to slide