Airless sprayers for hardwall?

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dogsbreakfast

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Howdy. Drywall contractor here with an airless texture sprayer. Wondering why no one seems to spray their hardwall this way since it gives a far cleaner fan than the mono pump + compressor videos I've seen, would lay on a hell of a lot more volume, and doesn't need a compressor.

Would the shear from a piston pump's action kick off setting quicker than a rotor stator? I've never put a setting compound through it so am curious.

Are plastering contractors favouring progressive cavity pumps because the one machine will move any material (like S&C) or is there something unholy going to happen if I put a gypsum/lime mix through a piston pump at 3000+ psi?


Cheers.
 
Hi Dbk,
is the machine one of the gracos ? if so your doing a blinding first post for promoting it.

Now I do apologise sincerely if this is not the case, and if so then I am sure there will be one of the machine guys along to explain the fors and against etc.

Having only ever used g4s in the past I cant comment, as I just did as I was told back then.

Hello by the way and welcome.

Rock on !
 
Thanks for the responses guys. Not promoting, just asking of anyone has used an airless. Mine is a titan 12000sv petrol. No videos, sorry. It hasn't seen much use but I've sprayed level 5 drywall on several jobs over the last year and am curious about using it for hardwall skimming.

My concern is that the action of the piston and shear in the line will kick off setting and I'll have myself a $10k scuplture, or that my 3/8" lines will cake up like a Texan's arteries with no way to clean them.

I found that a 60 minute setting compound was kicking off in a mud tube (a goofball drywaller's tool) in a matter of minutes on the piston head, which is the cause of my concern. Are you guys seeing evidence of setting in your machines? Caking in the stator or lines? Or granules clogging your spray gun? Or does the harwall set up any faster on the wall if you sprayed it instead of troweled it on?
 
Not really sure but there must be a very good reason for it like clogging, grain size, premature setting etc. have looked at the Wagner machines which switch to more robust worm pumps for heavier plasters.....there'd be no need if the smaller airless units could handle it
 
Hi Goody. From what I've read, aggregated slurries tend to separate under higher pressures like you get with an airless and you get a packed line. Slurry pumping tradition seems to favour worm drives or hose pumps so I agree there's probably good reason for such pumps continuing to be used.

Nevertheless, the tech rep at titan told me I'd be ok to put grit through it as long as I kept the pressure low, but I never tried it since it just seemed like hammering a nail with something other than a hammer. And there's no way it would deliver 10mm builds with enough speed to justify the maintenance costs. If I were going to get into float and set work or large sand finish runs I'd probably get something that could throw at least 100 l/m without overworking and hook it up to a Honda or pneumatic motor, and have a screw compressor alongside (really like the look of Kaeser M57 utility, but $$$). Still want to get around to acrylic application on tilt up concrete with such a rig but that's a project for another time.

At any rate I'm only proposing to put a gypsum gauged lime putty mix through the airless, or a manufacturers blend recommended for plasterboard veneer finishing.
 
Must be the accent. Woof. Been living in Perth, Aus since '99 tho. Spent a few years in the UK before that, mostly in the big smoke but worked as far north as Edinburgh and west to Cardiff. I found your plasterers pretty good but your tapers/jointers were hopeless, sorry to say.
 
Dogs breakfast.I just started thread on spray plastering. If you find out why it won't work please let me know as i think it could be perfect as spray much more even and quicker. Lots of advantages. When drywall is spayed this way finish far better and quicker. I was going to use a hopper so nothing sets in pipes. I need to know size of jets to use.
 
Hi, the heat generated from the piston will cause the plaster to go off quicker so you would probably need to have a wetter mix than usual. Is it a Graco T max 657 your using?
 
Hi jjp. I STILL haven't had time to muck around with setting muds so can't answer the key question. When I was spraying premix mud, I was using 25-45 thousands tips but a plasterer would probably want to use an x45 orifice or more since you guys are loading heavier. You'd need a strong machine though, since lots of paint sprayers specs top out at x23. Traditional paint sprayers might also struggle to pick up heavy bodied fluids.

I can't speak to orifice sizes on hopper guns but most models come with a disk on the outlet that you can rotate to select the size. Lots of texture contractors in the US use gravity hopper guns for their orange peel and heavier splatters for knockdown. It would be a bulletproof system from a setting-in-the-machinery perspective as well as having no worries with aggregate chewing up pump guts. Drawbacks I can see are the application speed being limited to drip speed, the impossibility of applying mixes too viscous to flow under their own weight, the need to manually load the hopper, and holding up the weight of the hopper. It would probably work fine, especially one with a fat neck, but a material feed line would be so nice for volume application. Bear in mind that air requirements for fine atomization are demanding. I haven't seen a 1 phase electric that I feel would provide near enough CFMs for a line fed system, but a hopper system might let the compressor recover while you're refilling. I'd like to go upwards of 100 CFMs. Conventional drywaller wisdom in the US seems to be 25 CFMs, but that might be simply because that's around the upper limit of lots of US piston units. I remember googling a chart that suggested a 1/2" diameter air line at minimum for decent CFMs without excessive pressure loss.
 
Hi quinns. Idk man, a thinner mix doesn't appreciably extend setting time in my experience. It would allow wimpier machines to pick it up and would reduce the PSIs needed to push it though.

I agree that the action of the piston, whether by heat or rubbing, could precipitate setting, but it seems like heat and rubbing would be an inevitability of any positive displacement pump, whether piston, worm, hose, lobe, etc. I'm more fearful of the fining of the material by rubbing action kicking off set than of the heat though, since the flowing material would attenuate heat build up.
 
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