Question on Setting Type Joint Compounds
bluewhale
| Posted in General Discussion on
Hey in regards to this
Does the Lightweight setting type jc(sandable) dry harder that the all purpose jc in the green buckets? For me the all pur jc stay chalky and if i dont seal it with something like Zinnser Gardz the paint will lift off. With the setting jc i have in the link above does anyone know if that dries harder or will i need to seal that as well? (heard about D-Mix but not sure if i want to try it this time around) From what i under stand the regular(green bag) setting jc dries hard but you cant sand it after it dries
Replies
The bag mix (hot) sompound dries to a harder surface than mud in buckets.
Either way you need to be sure to sweep/vacuum the wall thoroughly before you prime. It sounds like maybe you are leaving sanding dust on the wall.
Scratch and second with hot. Finish with green lid.
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I wipe the sanded surfaces with a damp tile sponge. Gets rid of loose powder and feathers the edges smoother.BruceT
I have used the Easy Sand products many times and have no problems with the prime or finish coat of paint lifting. It is much easier to sand than the Durabond products.
>>For me the all pur jc stay chalky and if i dont seal it with something like Zinnser Gardz the paint will lift off.
Are you cleaning the dust off the surface before you prime?
Dave
Yes i dont wipe it down with any liquid but i do dust it off then i used Behr primer first then painted
So the green bag duradond it just harder to sand but you can sand it? i got the impression you couldnt sand it at all
Durabond is much harder to sand, but it can be done; it's just much easier to finish with easysand on top and sand that.
When priming over a skim coat, use care in choosing your primer. I learned a good lesson this year after I skimmed over old plaster walls using DW compound--both setting and pre-mixed. I used a latex primer on some walls. When I went back and painted, the paint and primer peeled off. This did not happen on walls I primed with oil. Check out a thread from earlier this year, post #72406.7. A paint and DW compound expert here, Frankie, set me straight on what happened. Apparently the latex primer just sort of floats on the skim coat.
A good lesson: when in doubt use an oil primer.
Thanks again, Frankie--you're the best.
Marc
Apparently the latex primer just sort of floats on the skim coat.
What???
A skim coat is often completely sealed on the inside, so it dries out much slower and can absorb a significant amount of moisture quickly. Personally it sounds like you primed with too much primer and the moisture absorbed didn't have anywhere to go except to loosened the paint/skim coat bond.
Oil primer would work, as would going easy with a thin first coat.
Beer was created so carpenters wouldn't rule the world.
Bingo, give the man a cigar.
Don: Frankie's tips. It sounds right to me.......
"This is a typical result of priming a skimmed wall with a latex primer. See, latex primer is great for GWB because it soaks into the paper of the boards. However, latex primer literally floats on compound or plaster. It has minimal bonding ability to such a surface.
USG will tell you the same thing. So will Benjamin Moore.
If you did a VERY light skim over GWB you may have gotten lucky if the latex primer was able to get in contact with the paper face.
Alkyd (oil) primer actually soaks into the compound or plaster. That is what creates the bond strength.
Peel off as much of the latex primer as you can. Doing it sooner rather than later will serve you best. The primer will not have sured and will come off in rubbery sheets. After it cures and become brittle, it will come off in chips and you will damage more of the walls by the add'l scraping required. Leave alone whatever actually did bond to the compound. If it ain't broke, don't fix it.
After scraping, repair any gouges with compound, readymix or setting type, sand and reprime with an alkyd (oil) primer. Then you can paint using a latex finish paint.
Frankie
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>>latex primer literally floats on compound or plaster<<That's crazy. Why doesn't latex primer float right off your taped and mudded areas? Same joint compound used there as in skim coating. Some of those areas could be pretty thick, preventing primer moisture from "soaking into the paper of the boards".
Hi,
In the few rooms I have done for myself, I use regular setting type compound because I like the hardness. The green cover bucket compound is too soft for me, especially under tile. I do a top coat of the green cover though, because the setting type usually leaves bubbles. The easiest way to sand setting type is using a random orbital sander hooked to a vacuum with 60 or 80 grit.
I used Behr for the first few rooms, but it pulled right off. I switched to Benjamin Moore, and it seems to stick better to joint compound. It didn't stick to a ceiling I had plastered, except where I had gone over it with green cover joint compound. Blue tape pulled the paint right off *(&^%$%!!!! :>(
>>> It didn't stick to a ceiling I had plastered
was the plaster fully cured?
My guys like using light weight jc to embed tape and second coat and skim coat with the setting type. Its a pain to work with but the results are good. We almost never use the standard joint coumpound any more. When we texture (roll or stomp) we mix jc with paint for a little body. It also help seal and if it is a roll texture we never need to prime.
Hey with the Lightweight Setting jc after its dry should i wipe it down with a damp cloth(no too damp) to stop the dust that pops up when i wipe it with a dry cloth?
Any compound will continue to chalk (create a light dust when rubbed) until it's primed/painted. I usually just use my hand to dust the joints. For large areas, I might use a broom or a VERY lightly damp rag/sponge.
Sometimes, if there's too much dust on the wall when it's primed, it will create little lumps that look like lint stuck in the primer coat. It's easy to sand these off before topcoating.
What you don't want to do is actually wet the compound because that can create problems with the compound adhering to itself.
i cant figure whats going wrong this time i use the sandable lightweight setting joint compound with a thin coat i let it dry sanded it took a moist rag and wiped it down to get the dust off. I waited then applied the Sherwin Williams water based pro block primer and sealer several hours later i could peel the pro block off. Its like when you put elmers glue on your hand then after it dries you can peel it off. Maybe ill wait a whole 24 hours this time after i apply the sealer
In my previous post I cautioned against too much moisture in the rag/sponge that is used to remove excess dust. It's very easy to have too much moisture. Better to have none.
Just sweep the excess dust off the walls. prime. Lightly sand. And paint.
If I'm remembering right, SW ProBlock is quite thick. Compound is not as porous as drywall and you don't need (or want) a thick coat of primer. The ProBlock should work fine (even though it's not specifically recommended by SW for this purpose), but apply a light coat. You can even thin it a bit.
It sounds like you would be better off with a simple flat white paint to prime. If you want to add a thick primer after, at least you don't have to worry about it peeling.
Whatever you do only use enough paint/primer to barely cover the surface.
I don't let anyone wipe down the wall with a damp rag, even though many like to. All I've seen are problems that shouldn't be there.
Best of luck :-)