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Spraying water borne finish cleaning advice

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Forum topic by Thorbjorn88 posted 04-05-2021 04:32 PM 558 views 0 times favorited 6 replies Add to Favorites Watch
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Thorbjorn88

220 posts in 1225 days


04-05-2021 04:32 PM

I’ve been preparing to spray two guitars with waterborne finish. I’m using target coatings em6000. I’ve watched a lot of videos including a course I purchased from O’Brien guitars where someone finishes a guitar with this exact finish. So I’m feeling fairly confident about actually spraying but I’m not sure about some of the practical things about cleaning the gun.

1. If I wait 45 minutes between each coat do I need to completely disassemble the gun and wash with soap and water?

2. Is it ok to wash the gun in my kitchen sink if I wash the sink after? I know waterbase is lower VOC but I’m sure you wouldn’t want to eat it. I’m probably being paranoid but is there a chance I contaminate my sink then wash a dish with it etc…

3. Any other practical considerations that I should be aware of?

-- Dave


6 replies so far

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BurlyBob

8855 posts in 3349 days


#1 posted 04-05-2021 05:24 PM

What I did was take the canister off the spray gun put a piece of plastic wrap on the top and secure it with a rubber band. I’d submerge the spray gun in a bucket of water, till I needed for the next coat. I’d even leave it overnight like that. Also I did clean my spray gun in the kitchen sink with no problems. We’ve got a stainless steel sink so clean up was a breeze. I know that cleaning with hot water made the job a lot easier.

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CaptainKlutz

4451 posts in 2578 days


#2 posted 04-06-2021 09:25 AM

You are in Tuscon, which means low humidity and high temperatures.
In Arizona, coatings skin over faster than spec sheets suggest.
Coating inside your equipment dries quick too.

With more than 10min re-coat window; will run cleaning solvent through gun, but don’t tear gun down. If re-coat time is longer than 60 min, often will break down and clean the gun. But it depends on finish type. I don’t leave any post catalyzed finishes in gun between coats; just in case I get interrupted. On other end of spectrum, there is solvent pre-cat lacquer; where you leave finish in gun for days/weeks, with only quick tip clean between uses. :)

For WB, will use water to flush gun clean, and then water/alcohol blend to as final clean between coats. Leave the solvent blend in the gun. Before I start, will spray the solvent onto paper, looking for residue. If found, remove the cap and tip to ensure there is no crud. Wash with alcohol/water or maybe acetone if find any serious crud.

As far as safety of WB lacquer in kitchen sink?
Lacquer is blend of shellac and tree resin. Edible stuff for most part. Acrylic modification makes it something you won’t want around food when wet. IMHO – As long as you clean/dry the sink thoroughly after cleaning your gun, rest of house should be safe.
TBH – I find it easier to make my mess outside in 5 gallon bucket?
But then, #IAMAKLUTZ and splash junk everywhere. :)

I use my guns for both WB and solvent finishes. So while I clean WB finish with water, ALWAYS use acetone as final clean for the gun tear down. I keep a 1 gallon paint can with used acetone in it. The finish settles to bottom between uses, and can reuse acetone for cleaning till it evaporates. Can even dunk the gun inside the can to clean it too. :)

You are running out of cool weather soon. Be sure to spray in morning, before it gets too hot.

IME – AZ temperatures above 85° and below ~25% RH, tend to require retarder in just about any spray coating to get decent wet out. Even water base coatings need thinning or retarder in AZ environment. Target sells Glycol Ether DPM/water blend as retarder. I spray enough solvent coatings, that I use Butyl Cellosolve (or Glycol Ether EB) plus water, as retarder for most WB coatings. It works in both water and some solvent based coatings, and is available locally at automotive paint distributors and/or commercial wood coatings distributor. Spraying WB does not mean you can ditch the respirator. So I have no issue using solvent retarder with WB, even if it ruins the low VOC certification of coating as sprayed.

Hope this helps.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

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AlaskaGuy

6572 posts in 3392 days


#3 posted 04-06-2021 03:29 PM

I have sprayed 4 different brands of Water based topcoats mostly in a gravity feed gun. I have never cleaned between coats. Sometimes 4-5 hours between coats never had a problem. When you’re done with a coat take a wet cloth and wipe the air cap down well. Keep an eye on the air cap while spraying I have noticed some finishes like to dry and build on the air cap during spraying secessions.

I have never sprayed in hot weather. Around here is usually turn on the heat to get the shop up to 70.

-- Alaskan's for Global warming!

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Thorbjorn88

220 posts in 1225 days


#4 posted 04-06-2021 04:31 PM


IME – AZ temperatures above 85° and below ~25% RH, tend to require retarder in just about any spray coating to get decent wet out. Even water base coatings need thinning or retarder in AZ environment. Target sells Glycol Ether DPM/water blend as retarder. I spray enough solvent coatings, that I use Butyl Cellosolve (or Glycol Ether EB) plus water, as retarder for most WB coatings. It works in both water and some solvent based coatings, and is available locally at automotive paint distributors and/or commercial wood coatings distributor. Spraying WB does not mean you can ditch the respirator. So I have no issue using solvent retarder with WB, even if it ruins the low VOC certification of coating as sprayed.

- CaptainKlutz

Yes, thanks for thinking about that. I’m planning on spraying Wednesday through Saturday this week the weather says it will be up to 90 degrees and 10% humidity during the time I’ll be able to spray. I’m not sure how different my garage will be. I could put a humidifier in there and try to raise the humidity a little.

My local woodcraft has General Finishes Extender. I’m assuming it’s similar to any waterbased extender? I couldn’t find what it’s actually made of. Do you think I could use this with target coatings waterbase lacquer?

https://generalfinishes.com/wood-finishes-professional/wood-finishing-additives-miscellaneous/extender

I can also try to find an automotive paint supplier or commercial wood coatings distributor around here.

-- Dave

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CaptainKlutz

4451 posts in 2578 days


#5 posted 04-07-2021 02:32 PM

I could put a humidifier in there and try to raise the humidity a little.
IMHO – Won’t make much difference. Would need to put gallons of water into air to lift normal < 10% RH

My local woodcraft has General Finishes Extender. I m assuming it s similar to any waterbased extender?
Sorry, but no. The Enduro extender is 30% Propylene glycol, rest water. GF price for 8oz of that blend is same as Amadud charges for quart of 100% edible grade Propylene glycol. I like and use Propylene glycol as retarder for Mohawk Ultra penetrating dye stains, DIY Transtint blends, or other WB stains. But would not use it for TC WB lacquer.

try to find an automotive paint supplier or commercial wood coatings distributor around here.
Lived there long ago, before moving into PHX east valley; so things might have changed?
Try calling these folks:
- Hood Distribution on S Toole Ave (carry Mohawk finishes and some solvents)
- KC Auto Paint on 27th St (Wesco branch that carries 4-5 different auto paint brands, and generic solvents)
- FinishMaster on N. Stone ave (lil more expensive than Wesco, with a lot of private label/repackaged solvents)
- Sunbelt Coatings just north of Prince Rd. (used to carry Lemar brand Wood coatings by Benjamin Moore)
- SW Commercial store on Speedway. (Some commercial SW carry wood coatings, and solvents. Butyl Cellosolve is PN R6K25 and is recommended retarder for their Kem Aqua line.)

FWIW – EM6000 is only 30% solids, and can be sprayed straight from can. If you spray in morning, before it reaches 85° & while RH is still 20-25%; might need nothing more than a splash of distilled water? Won’t know till you spray the coating and gain some experience. If you get orange peel, or rough uneven surface; then add 5-10% water. If that doesn’t work, then add 5-10% Butyl Cellosolve and 5% water. Sorry to say, but it is a learning curve with every new WB coating, in a new environment.

One more tip: Be gentle when mixing your finish with water/retarder. Don’t add solvent and shake violently. The heavy body of WB acrylics can create/hold micro bubbles, especially if you get angry when mixing. It’s another reason WB finishes are more challenging than solvent wood coatings. Butyl Cellosolve is a fix to give coating more open time, which gives bubbles time to disappear if you find them.

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

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Thorbjorn88

220 posts in 1225 days


#6 posted 04-13-2021 04:39 PM

Thanks CaptainKlutz for all the very useful information!

-- Dave

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