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  • cleaning hvlp gun

    using a fuji gxpc gravity cup for water base products, soap and water is what i been using to clean gun with , any one use acetone or denatured alcohol ? I under stand mineral spirts is a no ? , just curious as to methods others are using
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  • #2

    Re: cleaning hvlp gun

    For waterbased products, I don't even use soap - just hot water.

    I don't have plumbing in my detached shop, so I have to do the main cleaning in the house at the laundry sink.

    First, in the shop, I empty the gun and then use some blue shop towels to wipe out the residual finish as best as possible. Then I pour some water from a jug into the gun, shake it around, and then reconnect the air and spray it through into a disposal bucket for a few minutes. At this point the bulk of the finish is cleaned out of the gun and I consider it "pre-cleaned."

    In the past, I would often just set the pre-cleaned gun on the shelf by the door and take it in with me for the full cleaning the next time I went into the house, but I discovered that if I clean it within ten minutes, the cleaning is about ten times easier! So now after pre-cleaning, I head into the house immediately.

    Once in the house, I have a cleaning kit that I assembled myself, just an assortment of brushes and bottle washers in a tool box, along with the various tools needed to disassemble the gun. I run the hot water (helps to keep your gloves on) and fully disassemble the gun and pressure cup. Often just the running hot water alone is enough to clean away all the remaining finish, but if not, a quick scrub with a brush always does.

    Once clean, I re-assemble the gun, pouring some water in the cup, and head back out to the shop. I connect the air and give a little spray, just enough to get the water running through it, then just leave it there with water in the lines.

    Before next use, you have to make sure to empty it and then spray it dry to make sure you've got all the water out, or your first spray of new finish will be wicked diluted!


    This method has worked well for me for years.

    I rarely spray solvent based products. When I do spray solvent lacquer, which I intentionally avoid, I generally follow the same process, except that instead of being in the house at the laundry sink with hot water, I'm in the shop at a wash basin with a can of lacquer thinner and the exhaust fan running. That cleaning is actually easier, since lacquer solvent based finishes, I find, clean up exceptionally easy with solvent! But over all I dislike the smell and everything else related to it, and as a rule don't use solvent finishes. Plus, I think the solvent dries out the various rubber or plastic gaskets in the gun, so whenever I've solvent cleaned, I usually lube those up with a light touch of oil.

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    • #3

      Re: cleaning hvlp gun

      Google search How To Hand Clean Your SATA Automotive Refinish Gun - YouTube

      It might Help.

      "Do it Right!"

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      • #4

        Re: cleaning hvlp gun

        In finishing school our instructor impressed on us NOT to use hot water to flush waterbased finishes out of the gun. His reasoning was simple: unlike their solvent based cousins where resins are in solution, the resins in waterbased finishes are a suspension and are removed by physical action not chemical reaction so exposing them to heat will start the catalytic process of curing. Basically the resins will gel up and may end up sticking to the inner parts of the gun. Don't know if you have ever noticed but waterbased will actually set up under water, and even under lacquer thinners DAMHIKT
        On the subject of adding soap/detergent, our instructor was also adamant that most dish soaps contained additives that were useless for this application, and could even start the setting up process as well as potentially damage the insides of some guns or leave residues that adversely affected the finish by being a potential source of fisheyes due to their ability to lower surface tension. His preferred additive was two or three drops of household ammonia.
        We were also instructed to thoroughly flush the gun, again with warm water and if we wanted to leave fluid in the lines to stop the seals drying out, to use distilled water only. His reasoning was that tap water contains minerals, the concentration and composition of which vary from area to area, and these can all settle out and form some sort of bond with the metal or plastic parts of the gun then detach when you started spraying again.
        This was about 20yrs ago and waterbased chemistry has evolved tremendously since but the lessons stuck with me.

        I only use acetone if I have a particularly stubborn residue or for my annual strip down and clean. It's a fantastic solvent and degunker but evaporates extremely quickly so can not be left in the spray gun for extended periods. I have found denatured alcohol works sometimes to remove gunk but is limited as a cleaning agent, mostly because it acts as a desiccant.

        I switch between waterbased and solvent based finishes and always leave lacquer thinners in the lines/guns. If spraying waterbased, I will wash out with warm water, then warm water/ammonia/ then clean water/ then denatured alcohol (to remove any residual water) then lacquer thinners. If the next job is solvent based I just flush out the thinners but if waterbased is called for I do an alcohol flush, then a clean water flush.
        About six months ago I tried a waterbased gun wash that is designed for the automotive finishing industry. It's expensive but seems to work OK judging by the amount of crud that came out of the gun and lines. There is a product to promote coagulation and settling of this residue but it is super expensive, so I just let time and gravity do their thing in tightly capped large glass jars before reusing.

        Hope that helps answer your questions
        Paul
        Last edited by Paul O in Paris; 11-08-2018, 03:24 PM.
        Woodwreck and MartyFromKingston like this.

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        • #5

          Re: cleaning hvlp gun

          Originally posted by Paul O in Paris View Post
          In finishing school our instructor impressed on us NOT to use hot water to flush waterbased finishes out of the gun. His reasoning was simple: unlike their solvent based cousins where resins are in solution, the resins in waterbased finishes are a suspension and are removed by physical action not chemical reaction so exposing them to heat will start the catalytic process of curing.
          Interesting, I wonder if that's still true. Often it's advised to warm the finish in order to get it to flow better, and I've done that on occasion and found it to work effectively. If heat jumpstarted the curing process, I would not expect that result. The other thing I know from experience is that when I first start washing the gun, when the hot water is first turned on it has to run a while before it's hot, and during that first period when I'm trying to wash with cool/warm water, I know that finish residue clings on quite stubbornly, but when the water finally gets hot, the residue melts away easily. I guess what I'm saying is, my experience doesn't align with what your instructor said. Perhaps, as you said, the WB products have simply changed in the last 20 years.

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          • #6

            Re: cleaning hvlp gun

            why I posted because all off a sudden , I got fish eye and nothing changed ? using dish soap and hot water ? used some accetone to clean gun out ? that ok

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            • #7

              Re: cleaning hvlp gun

              Originally posted by rickyw View Post
              why I posted because all off a sudden , I got fish eye and nothing changed ? using dish soap and hot water ? used some accetone to clean gun out ? that ok
              The fish eye may not be from your gun. The problem could be caused by something on the surface you are spraying.
              the other Ken
              ------
              "Each flitch, each board, each plant can have only one ideal use. The woodworker, applying a thousand skills, must find that ideal use and then shape the wood to realize its true potential" - George Nakashima

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              • #8

                Re: cleaning hvlp gun

                I agree with Ken. If you are cleaning your gun with the same products as always and you have never had problems before, then I seriously doubt it's the gun. You could run a little acetone through it, but that could dislodge some crud and you would have an extra set of problems. Maybe do that after you have finished this current project.
                Fisheye is most often caused by contamination of the surface being sprayed usually by coming into contact with an unclean surface or from microdroplets of something dropping out of the air. There are even reported incidences of a person's deodorant causing them. So has whatever you are spraying got dirty, have you used any aerosols in your shop area recently (WD 40 is a common cause)? Those are areas I would look to first.
                It could also be a contaminated batch of finish. What are you spraying and was it newly opened or a previously opened can? Was it stirred real well so there was almost nothing left on the bottom? Was anything added to the can?
                A long shot could be that your turbine is putting something into the air stream. One way to check is to disconnect the hose from the gun, wrap some white cloth or paper towel around the hose end, turn on the motor. let it warm up then turn off and inspect cloth/paper towel for any oily residue.
                There are other features that can look like fisheye, craters or solvent pop spring to mind and are caused either by the product one is using or the spray technique or both. If you have a pic that could help.
                It's frustrating and we've all been there, but it's solvable although it can be a lengthy process of elimination.
                Hang in there
                Paul

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                • #9

                  Re: cleaning hvlp gun

                  Originally posted by callee View Post

                  Perhaps, as you said, the WB products have simply changed in the last 20 years.
                  Ryan, waterbased finishes have made a quantum leap since I started spraying them, but I still don't use hot water for cleaning.
                  Waterbased starts to cure when the carrier loses full contact with the resin particles. This will happen to some extent if you leave a can for a long time and all the solids settle to the bottom thus isolating themselves from the carrier. There is a witches brew of chemicals in that liquid designed to delay curing until a specific set of conditions are met, so you can warm up a can of well stirred finish and it won't start to cure because the resins are surrounded by all these goodies in the carrier. Spray the finish on a surface and the thin layer doesn't have the same properties as a can full and the resins become separated from the carrier (as it evaporates) and start the amalgamation process. Heat will speed up this process, so the way it was explained to me was that flushing hot water will remove most of the carrier and will accelerate the curing of any resin that's left. It's probably not a big deal in a cup gun and regularly taking it apart and brushing it out will ensure there are no such problems. However, I have a 25ft line from my pressure pot to the gun and a 15ft line form my Kremlin pump to the gun and as I haven't come across any brushes that would work for those lengths I don't take any chances.
                  But I digress and am getting too far away from the OP's questions
                  Paul

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                  • #10

                    Re: cleaning hvlp gun

                    Paul I was just going through some PDF's for SW Kem Aqua products. To add/reenforce what is being discussed, this was their recommendation WB for cleanup.

                    "Clean tools/equipment immediately after use with water. Flush equipment with water followed by flushing with 2 parts water and 1 part Butyl Cellosolve R6K25 or Acetone R6K9."

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                    • #11

                      Re: cleaning hvlp gun

                      On a semi-related note - WOW! I was thinking about getting into spray finishes, but it sounds like a LOT of work to clean up and maintain your equipment.

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                      • #12

                        Re: cleaning hvlp gun

                        Did you check out my link?
                        "Do it Right!"

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                        • #13

                          Re: cleaning hvlp gun

                          Originally posted by rfielder View Post
                          On a semi-related note - WOW! I was thinking about getting into spray finishes, but it sounds like a LOT of work to clean up and maintain your equipment.
                          Not really , never make a judgement on what you read on a forum. I am not that much of an enviromentalist and still spray solvent based products. You do need good ventilation and really not suitable to spray in your basement. Cleans up very easily with thinners. I use a Kremlin system but started with a siphon feed gun and a 3 hp compressor. You can buy a Hvlp gun for under $100. I used a 20 gallon compressor for years and it works fine if you are not doing large jobs.

                          Brian
                          If your dreams don't scare you, you are not dreaming big enough

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                          • #14

                            Re: cleaning hvlp gun

                            Originally posted by John JMK View Post
                            l I was just going through some PDF's for SW Kem Aqua products.

                            John brings up a very important point, namely that the finish manufacturers provide detailed spec sheets on their products and how to use them. Some give more detail than others but there is a ton of information out there to help folks get the best out of their products.
                            IMO anyone who uses any kind of finish owes it to themselves to check these data sheets, which are usually readily available on the manufacturers' web site in the product description area.
                            The cleaning method John quoted is a simple yet effective way to keep a spray gun working. Butyl Cellusolve may be hard to get but Acetone is available at some hardware stores and can certainly be found at at the automotive stores that sell paints.

                            Paul


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                            • #15

                              Re: cleaning hvlp gun

                              Originally posted by rfielder View Post
                              I was thinking about getting into spray finishes, but it sounds like a LOT of work to clean up and maintain your equipment.
                              Any equipment needs regular cleaning but if you are getting put off by the details I posted remember that because I am a one man finishing and refinishing business, I place totally different demands on my equipment and use very different finishes than someone getting into spray finishing on a casual basis.
                              The simple cleaning method John quoted above will work well and it's hardly a lot of work to fill the gun cup and pull the trigger is it?
                              If you want to minimize the amount of cleaning then check out the 3M PPS system.
                              And as Brian said, don't get put off by what you read on an internet forum unless you know and/or trust the source.
                              Hope that clarifies some issues for you.
                              Paul
                              Last edited by Paul O in Paris; 11-10-2018, 08:32 AM.

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