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why not use an auto spray gun for home acrylic paints?

PostPosted: Mon Apr 04, 2011 4:52 pm
by justanothernoob
Hi there - dumb question for the day

I'm new to the site and did try the search in both this and the Body and Paint forum but couldn't find an answer - so please forgive me if I'm asking something that's already been answered.

Ok, here goes ...

I was lucky enough to inherit a Marquip 3 HP / 13 cfm air compressor from a mate moving to Aussie (from NZ) - I've spent some money on having it serviced and buying attachments for it.

At some stage I'll be using it to repaint a 1972 Landcruiser FJ40 that I'm renovating and also an AC Cobra replica that I'm building. At this stage I'm thinking that I'll probably go for the Eastwood Concours HVLP gun as it only requires 4cfm at 29 psi and is a pretty competitively priced unit.

But I got to thinking: why can't I use this to also repaint the inside of my house? The local paint-suppliers have all told me that I need to buy Wagner airless kit. But my experience to-date has been that with only 4.5 million inhabitants, our local suppliers generally dispense advice that is often based more on the biased advice of distributor sales-reps and not necessarily based on experience. And it's also convenient (for them) that they want to sell me a $1700 Wagner unit on top of the auto spray gun!

From what I've been able to find out on the internerd, it seems that nozzle size will be one issue: auto spray guns tend to use 1.2-2 mm nozzle sizes whereas acrylic house-paint seems to need about 4.0mm (0.17 inch) nozzle size. Is it possible to get a 4.0 mm nozzle for an auto spray gun? I saw on this forum that someone had tried drilling an 2.0 mm nozzle but not sure what the results were.

I've also been told that (by local suppliers) that auto spray-guns generally can't handle acrylic paint. Is that still the case with the new breed of auto spray guns that are designed for water-born paint?

Or should I simply consider using oil paint (house) - would that work any better?

Anybody got any thoughts / advice to offer?

Thanks in advance for your help ;o)

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Mon Apr 04, 2011 5:29 pm
by chris
I've shot plenty of latex house paint through my cheap "astro" brand 1.7mm tip pressure-pot gun with no problem. Trick is to reduce the paint by about 10% with distilled water, and another 10% to 15% with Floetrol, which is a brand name for a latex paint flow and leveling enhancer -- check with your local house paint supply specialty shop to see what you guys have.

Here is an example -- a column for a fireplace I recently built; shot with Sherwin pro-classic latex the very way I described. Goes on like glass, as good as any car paint I've ever sprayed.


Now an alternative is to just rent the professional house paint equipment...if you are just doing one job that's probably something to consider. Also, remember you will be dealing with overspray so now maybe the old traditional paint roller is not looking too bad ;-)


P.S. here is the exact gun I'm talking about: Astro 2qt gun

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Mon Apr 04, 2011 5:35 pm
by tomsteve
you sure could paint the inside of your house and use latex for it, but heres a few things to consider. what size cup on your gun??? gonna have to refill quite often. compressor will run a lot, causing heat and moisture, both enemies. when sprayed for a period of time, latex can build up on the tip and cause problems. i spray latex paints, but not on large areas. airless sprayers are the bees knees for that application.

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Mon Apr 04, 2011 7:58 pm
by justanothernoob
Thanks Chris - appreciate you taking the time to explain exactly what and how ;o)

I'm repainting EVERY ROOM in the house - that's 10 rooms, 4 with 4 metre studs (thanks to the 45 degree-pitched roof) so I'm planning on taking my time!

I'm a project manager by trade so I know the old rule of "I can do it cheap, I can do it quick, I can do it well --- pick any TWO!"

In this case the 21 month old and 4 year old sons have made it clear to me that I'm short on $$$ :lol:
And I know exactly what a pedantic little so-and-so I am and that I won't be able to live with a poorly done job.
Which means I'm going to have to settle with taking the time to do it right. So I'll probably just do one room at a time - for the big rooms it may even be just one wall at a time.

Chris - you mentioned that you used a 1.7mm nozzle - would you expect any major changes to your thinning measures for a 1.8 or 2.0 mm nozzle?

Tomsteve - good point on the pot size - I'll need to work out coverage and paint volumes required for each room / wall - might need to go to something like that Astro 2qt system Chris used.

hmmmm ... that's given me some stuff to consider and talk to the local paint shop about. Thanks gents - will let you know what I go with and will post before and after shots as I slowly but surely work my way through the house! Then I'll be asking for advice about painting the external weatherboards and the iron roof!!! :roll:

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Mon Apr 04, 2011 8:24 pm
by badsix
check and see if you can't rent an airless, it will be much better and faster and probibly end up costing less i can rent them here for about 25 - 35 a day. you could realy cheep out and just use a roller, depending on the texture on your walls you should roll them anyway :)

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Mon Apr 04, 2011 8:25 pm
by chris
On a 2.0 tip I'd probably skip the distilled water and just thin it with 10% Floetrol. It's pretty easy to dial this stuff in.

The 2qt cup is perfect for my woodworking projects but for a room I'd probably get the 9qt version. Still a LOT less expensive than a dedicated Wagner paint system, if you already have a good source of compressed air.


Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Tue Apr 05, 2011 2:39 am
by justanothernoob
Thanks guys.

The guy I'll probably buy my paint from is one of those chemical mixer guys that mixes paint up for commercial painters. Last year I got a 10 litre tub from him that's designed for use with commercial airless systems - I think that basically they have their own 'lid' that clips onto the 10 litre tub. Guess I need to find a similar sort of system that I can use with my compressor - more internerd surfing required!

Will have to phone around a few places tomorrow re. hiring costs for an airless system.

Chris - if I do go with using an auto spray-gun, is there anything different I need to do re. cleaning of equipment other than if I were using normal auto water-borne paint?

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Tue Apr 05, 2011 9:00 am
by chris
nah, I just clean mine with soap & water and blow it dry really well. If I'm shooting something like Zinsser BIN primer then I use ammonia. Whatever the back of the can says to use for cleanup :-)


Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Tue Apr 05, 2011 4:37 pm
by justanothernoob
ah - just follow the instructions - good to know - although given that I used to be a techie engineer I might have difficulty following instructions! That's if I even get around to reading them!!! :lol:

Re: why not use an auto spray gun for home acrylic paints?

PostPosted: Fri Apr 15, 2011 6:07 am
by justanothernoob
So in trying to find good gear to hire ... I talked to a couple of professional paint suppliers and while they highly recommend the Wagner airless systems they don't hire gear out because "are you kidding - we used to but people treat the gear like crap and don't clean it properly" ... which got me thinking that I won't bother trying to find a hire-place with some crapped out, gunked up kit that previous users haven't cleaned properly!

So I picked up this 10 litre pressure pot today -

Will be skimming, sanding and prepping a wall for painting next week - the GIB (plasterboard sheets - not sure if you use this product outside of NZ) is pretty old so I'll use an oil-based primer before I spray-paint the wall to stop any of the GIB board chemicals tainting the pigment in the acrylic.

Apparently this pressure pot is designed for use with acrylic paints and not oil-based or enamel so I'll only use it for the topcoats. Comes with a 2.0mm nozzle but I'll probably still be cautious and thin the paint down by 10-15% (unless anyone has any alternative advice).

Looking forward to lots of prep and masking-up next week ... NARRRRRRRRRRT! ;oP

Photos and updates to follow next week - hope you all have a great weekend ;o)