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Thinning paint for spraying - Dialing it in

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Forum topic by Dave posted 05-22-2014 12:07 AM 1108 views 0 times favorited 20 replies Add to Favorites Watch
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Dave

115 posts in 1850 days


05-22-2014 12:07 AM

Topic tags/keywords: finishing painting spraying hvlp earlex benjamin moore thinning question spray gun

I’m about to paint cabinets with Benjamin Moore Advance Waterborne Alkyd and would like to spray it with my Earlex 5500.

Out of the can, the viscosity of BM Advance is over 400 seconds. The Earlex will spray anything 160 seconds or better but I saw someone say on another thread that they can spray the BM Advance just fine after thinning it 10%.

But, I’m a cheap lazy B:$tard so before I thin a quart and potentially waste paint & cleanup time, I wanted to see if I could verify that statement. It seems hard to believe that adding 1 part water (which has a viscosity around 12 seconds) to 9 parts BW advance would bring its viscosity from 400+ seconds down to under 160.

Anybody out there want to try a simple science experiment? If not, maybe the folks who’ve sprayed this successfully can convince me to give it a try :)

Thanks in advance for the help, everyone!

Edit: After reading the very useful advice below, I got a good result by:

1. Thinning the BM Advance by 10% with tap water and mixing it thoroughly – this cut the viscosity from 400 down to 160 or so.
2. Using a 2mm needle
3. Mixing the thinned paint (I made a 300 mL batch) for 2 minutes with a 1 gallon helix paint mixer from Home Depot:

Surprisingly, the last step was absolutely critical. I’d tried the exact same mix of paint earlier and hand-stirred it for a minute instead of mixing with the mixer above. The paint did not flow well out of the gun and I got a very rough finish. I didn’t measure the viscosity of the drill-stirred mix but it definitely seemed to flow better.

Now it’s time to spray some cabinets. Thanks, everyone, for the advice!

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright


20 replies so far

View badcrayon's profile

badcrayon

33 posts in 474 days


#1 posted 05-22-2014 12:14 AM

I work for a paint company I personally wouldn’t thin the product more than 20% . More with start to break down the paint and could cause it to fail.

-- Bad Crayon Studio

View Woodbridge's profile

Woodbridge

2721 posts in 1071 days


#2 posted 05-22-2014 12:31 AM

I attended a seminar given by an Earlex rep and he said that you would thin paint somewhere between 10-15%

-- Peter, Woodbridge, Ontario

View Fred Hargis's profile

Fred Hargis

1783 posts in 1146 days


#3 posted 05-22-2014 11:10 AM

You will be quite amazed at how quickly the flow increases with the addition of a little thinner. That said, water borne finishes cannot be thinned on a wim…be sure to check what the max is that BM suggests and don’t exceed that. To do so may impact the chemistry of the paint.

-- Our village hasn't lost it's idiot, we sent 'em to Washington.

View Dave's profile

Dave

115 posts in 1850 days


#4 posted 05-23-2014 02:10 AM

Thanks guys. I’ve seen the BM recommendation to thin “slightly” if needed for airless sprayers. I’m wondering if 10% will get me anywhere close to the needed viscosity – Fred’s comment about how fast things start to thin out has me encouraged, though.

Fred, do you know how the chemistry is affected? Is it sheen, color, bonding ability, or “all of the above”?

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

View firefighterontheside's profile

firefighterontheside

4288 posts in 510 days


#5 posted 05-23-2014 02:24 AM

Fred, I just sprayed some water based poly thru my 5500 today. I asked earlextech about how much to thin and he said about 10%. I doubt I went that far and it worked perfectly. I’d be interested to know how yours works out.

-- Bill M. I love my job as a firefighter, but nothing gives me the satisfaction of running my hand over a project that I have built and just finished sanding.

View Dave's profile

Dave

115 posts in 1850 days


#6 posted 05-25-2014 01:09 AM

I don’t know how the water-based poly compares to the BM Advance on viscosity…how long does it take to drain through the magic viscosity cup before it’s thinned?

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

View ducky911's profile

ducky911

223 posts in 1443 days


#7 posted 05-25-2014 03:52 PM

Just finished a project with latex paint. You need to thin until it works. I have both the earlex 5000 and Fuji 4 stage.
I thin the paint with 10 percent water.
double the leveling stuff frestol (sp) recommended
than waterbase poly until I get it to where I want it.

thin down to 30 sec and see how you like it. My project I just did came out perfect. I will try to edit this in a few with a picture.

I have been told that stiring with a drill helps but have yet to try it.

at 160sec your earlex will not work. try a small cup of my meothod

View ducky911's profile

ducky911

223 posts in 1443 days


#8 posted 05-25-2014 04:01 PM

another pic

View RocketDogs's profile

RocketDogs

6 posts in 135 days


#9 posted 05-25-2014 05:16 PM

This may help…. I have sprayed BM Advance and SW pro Classic….with excellent results in my Earlex 6900
This is what I do….I start with 32 oz of paint in a separate container add 1 viscosity cup( 4 oz )of water….2 oz of Flotrol
( Some BM paints you have to use BM’s paint conditioner but not Advance)....mix with a low speed drill for 2 minutes….per Earlextech advice…..then filter into another container…..then mix with a stir stick….Here is the important part…....When the paint quits running off the stick in a stream….within 1 or two seconds….it should drip like a rain drop….perfect circular beads….if not add 1/2 to 1 oz more water and mix with the stick until you get the rain drops at the end…..this method ended all the mystery about thinning for me and my Earlex 6900

FWIW…BM Advance flowed well with about 5 oz of water…..And SW proclassic worked very well with 6 oz of water
Both got 2 oz of Flotrol
Hope this helps

RocketDogs

View Dave's profile

Dave

115 posts in 1850 days


#10 posted 05-25-2014 06:16 PM

ducky911, great finish! thanks for the info.

RocketDogs, that’s really helpful – I really appreciate the detailed description!

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

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RocketDogs

6 posts in 135 days


#11 posted 05-25-2014 08:56 PM

If you want cheap paint to practice with Sherwin Williams has sample quarts for around $7.00 a quart…..same thickness as regular paint….but it will fade over time so its not really paint….plus you get to keep the handy quart container….her is a link

http://www.sherwin-williams.com/homeowners/products/catalog/color_to_go/

RocketDogs

View Dave's profile

Dave

115 posts in 1850 days


#12 posted 05-28-2014 01:45 AM

Thanks, RocketDogs.

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

View Dave's profile

Dave

115 posts in 1850 days


#13 posted 06-28-2014 08:18 PM

I wanted to post a follow-up. After the advice above I thinned the BM Advance 10% (1 part water to 10 parts paint) and re-measured. The viscosity was just a hair over 160 sec – down from over 400 sec without thinning.

When I sprayed the stuff I got OK atomization – not awesome, not horrible – but then I realized during cleanup that I also had my 2mm needle mounted. That’s probably the culprit behind the mediocre atomizing so I’ll try the next coat with a 1.5mm needle and dial back the paint flow a bit.

Once I get things tuned in I’ll post some pics. Thanks, all.

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

View Dave's profile

Dave

115 posts in 1850 days


#14 posted 07-01-2014 12:11 AM

Well, now I’m confused. Tonight I tried spraying the same 10% thinned BM advance with a 1.5mm tip, thinking the 2mm might have been too big for complete atomization.

I adjusted the spray with the 1.5 and was still getting so-so atomization so I tried the smallest paint flow I could…low enough that it took holding the gun stationary 4-5 seconds to even coat the spray pattern on the test sheet. Even so, I still got some splatter. I also opened up and tried some higher flows – all the way up to “splatter city”. No matter what I tried, nothing gave me good results. So, I picked the best compromise between splatter & paint flow and tried a coat of paint. I got similar results to my first spray with the 2mm tip but it took over twice as long due to the lower paint flow. So much for better atomization (at least with the BM advance) with the smaller needle.

So, my only conclusion is that the paint is STILL too thick. Could it something else I’m doing (or not doing)? Do I thin the BM Advance more than 10% (i.e. faster than 160 sec), go back to the 2mm needle and try again, buy a better gun, or go back to my Purdy brush (which is giving me a smoother finish than the gun so far)?

Thanks guys.

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

View Dave's profile

Dave

115 posts in 1850 days


#15 posted 07-07-2014 07:54 PM

I think I finally dialed in a good combination. I went back to the 2mm needle and the 10%-thinned BM Advance but this time I used a drill to stir it for 2 minutes instead of hand-stirring for 1 minute. It laid down with much less splatter and, while it’s still not a piano-grade finish, it was nice and smooth. Certainly good enough for my purposes.

I’d heard that’s the case with stirring these paints – something about the long molecules of paint lining up like spaghetti in a whirlpool when you stir well – which makes it easier to get out of the gun when you spray.

Whew, that was tedious – but a good lesson learned…

-- "I'm not afraid of heights. I'm afraid of widths." - Steven Wright

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