|
HVLP question spraying water-based poly
As a newbie to HVLP, I have encountered the following problem...
I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks |
HVLP question spraying water-based poly
On Nov 24, 10:25*pm, blueman wrote:
As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have sprayed the same product with a 2.0 tip on an HVLP gravity feed gun at 45 psi inlet pressure. Medium fan. It works a lot better in a cooler environment. |
HVLP question spraying water-based poly
To get a good, comprehensive answers to your questions, it would be
easier for you to simply search this group. The subject of HVLP spraying of water borne materials has been discussed completely several times. Any time you have spraying errors you can have a *multitude* of problems that will generate poor results. Some mimic others, so it is best to get a list of common spraying problems and their diagnosis and begin from there with your own equipment. I spent a lot of time writing out the way to properly set up your gun for spraying a long while back, and I was contacted by more than a few that thought the info I put out was helpful. It might be to you as well. FWIW, I think Rob may be on to something. MOST guns (not all) that come with one tip use a 1.4 to 1.7 mm tip. If you are in that range, it might not be large enough to spray your finish without thinning. If you didn't get another tip with the gun (the 2mm is intended for unthinned latex), try thinning your material about 10% with distilled water, then shooting it. I would also suggest that you find a good book(s) on spray technique. There are a lot of good ones out there, and they can help you troubleshoot your problems. Some of those books will help you realize that there are too many variables to troubleshoot ACCURATELY without a ton of info. They may also be able to help you figure out what you are doing wrong as well. Plan on investing some time and money in learning the spray process. It is no different from any other part of learning a craft, but it seems to be the biggest enemy of wood workers as they feel like it is something that they can learn from osmosis. You can spray material out of a gun by simply hooking it up. But to shoot a well laid, consistent finish is something that takes time, practice, and above all, patience. Robert |
HVLP question spraying water-based poly
blueman wrote:
As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). I purchased the baby brother to that gun (46719) for detail work. Almost all of my painting is with automotive refinishes, and I don't do much at all with the stuff you're working with, but I'll share some comments and experiences in general. First off - don't assume that you'll get sags or runs on vertical surfaces. If your gun is set up right, the material is the proper viscosity, and your technique is right, you should easily be able to spray vertical or horizontal surfaces with that gun. If you have to put on what you feel is a heavy coat to get a wet coverage, then you probably need to either thin your material or step up to a larger tip. As well - be careful with HVLP about cranking your input pressure up too much. More is not better with a gun like this. HVLP does not atomize like the old guns we were used to and it really takes some experimenting to get used to your gun. - Is this normal or am I doing something wrong? Of course - it's always the sprayer's fault - never the gun's fault... - If so what are the likely causes and corrections? Generally - too high input air pressure, or too small a tip, or too thick a mixture. Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. Try cranking that back - a good bit. Try 15-20 psi. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI Too high for most HVLP guns. - Adjust the fluid volume Good adjustment - you'll be working with this adjustment a lot. - Adjust the spray pattern (more round vs. more oval) Don't use this to get the right amount of material down. Use this to get the right coverage pattern. If you have to needle the thing down to a small pattern in order to get a decent coverage, you need to go back and look at viscosity, tip size, and pressure. - Adjust the distance to the object (from maybe 8 to 16 inches) 16" is a mile away. Try moving in to 6-8" - Adjust the speed at which I sweep across the object Always. Different materials will require different application speeds. Thicker equals slower. While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Fairly high viscosity would not equate to spraying well. You might want to add 25% more reducer than you've been using and observe the differences. -- -Mike- |
HVLP question spraying water-based poly
On Wed, 24 Nov 2010 22:25:18 -0500, blueman wrote:
As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Condolences. Perhaps you could thin it with Floetrol. I believe that Naily has sprayed that and will be piping up soon. -- Experience is a good teacher, but she send in terrific bills. -- Minna Thomas Antrim |
HVLP question spraying water-based poly
On Nov 25, 3:46*am, "
wrote: FWIW, I think Rob may be on to something. *MOST guns (not all) that come with one tip use a 1.4 to 1.7 mm tip. *If you are in that range, it might not be large enough to spray your finish without thinning. If you didn't get another tip with the gun (the 2mm is intended for unthinned latex), try thinning your material about 10% with distilled water, then shooting it. I bought that 2.0 gravity gun specifically for squirting Sikkens 3+1 primer. An automotive product that just works wonders on MDF's edges and routed profiles. The build is insane, the sandability fantastic. (For some reason my spellchecker balks at sandability...oh well.) That stuff is so thick, it needs a tip that large. It's an Iwata LPH440-201. I took it, all nice and clean to my buddy's booth as I needed to blow some thanes on a few sheets of luan. I checked the Polycryl with a viscosity cup and looked almost too thin for the 2.0 (IMHO, a 1.8 would have done it too). I wasn't about to dirty up his pot-fed equipment. (Waterbased snot in HIS guns? He would have murderized me.) It went on so nice even though I was using a LOT of air to blow that snot apart. I have revisited the same spray schedule since with the same results.... and if it works, don't mess with it. |
HVLP question spraying water-based poly
|
HVLP question spraying water-based poly
blueman wrote:
As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have had better luck spraying Fuhr water based products. I sprayed polycrylic and it never leveled out as nicely as Fuhr. Cm |
HVLP question spraying water-based poly
"cm" wrote in message
... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have had better luck spraying Fuhr water based products. I sprayed polycrylic and it never leveled out as nicely as Fuhr. Cm Especially if you're after that fuhrry look. :-) Max |
HVLP question spraying water-based poly
On Nov 26, 10:28*am, "Max" wrote:
"cm" wrote in message ... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have had better luck spraying Fuhr water based products. I sprayed polycrylic and it never leveled out as nicely as Fuhr. Cm Especially if you're after that fuhrry look. *:-) Max Ahw, fuhr crying out loud!! |
HVLP question spraying water-based poly
On Fri, 26 Nov 2010 08:29:37 -0800 (PST), Robatoy
wrote: On Nov 26, 10:28*am, "Max" wrote: "cm" wrote in message ... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have had better luck spraying Fuhr water based products. I sprayed polycrylic and it never leveled out as nicely as Fuhr. Cm Especially if you're after that fuhrry look. *:-) Max Ahw, fuhr crying out loud!! Poly-shades/crylic are a fuhr cry from decent finishes. -- Education should provide the tools for a widening and deepening of life, for increased appreciation of all one sees or experiences. It should equip a person to live life well, to understand what is happening around him, for to live life well one must live life with awareness. -- Louis L'Amour |
HVLP question spraying water-based poly
On Nov 26, 5:15*pm, Larry Jaques
wrote: On Fri, 26 Nov 2010 08:29:37 -0800 (PST), Robatoy wrote: On Nov 26, 10:28*am, "Max" wrote: "cm" wrote in message ... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have had better luck spraying Fuhr water based products. I sprayed polycrylic and it never leveled out as nicely as Fuhr. Cm Especially if you're after that fuhrry look. *:-) Max Ahw, fuhr crying out loud!! Poly-shades/crylic are a fuhr cry from decent finishes. -- Education should provide the tools for a widening and deepening of life, for increased appreciation of all one sees or experiences. It should equip a person to live life well, to understand what is happening around him, for to live life well one must live life with awareness. * * * * * * * * * * * * * * * * * * * *-- Louis L'Amour Those finishes are targeted at lazy people who want quick 'n dirty. They excel at that job. French polish? Nope. |
HVLP question spraying water-based poly
In article ,
says... J. Clarke wrote: In article , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. So tell us the engineering definition of "hardness" and quote your source. |
HVLP question spraying water-based poly
On Sat, 27 Nov 2010 11:54:36 -0500, "J. Clarke" wrote:
In article , says... J. Clarke wrote: In article , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. So tell us the engineering definition of "hardness" and quote your source. "The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science." http://www.search.com/reference/Mohs...neral_hardness |
HVLP question spraying water-based poly
On Nov 27, 10:01*am, "dadiOH" wrote:
J. Clarke wrote: In article , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. *It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. Not to get all 'clarke' about this, but tire rubber is, in terms of hardness. very soft but very scratch resistant. |
HVLP question spraying water-based poly
On 11/27/10 11:50 AM, Robatoy wrote:
On Nov 27, 10:01 am, wrote: J. Clarke wrote: In , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. Not to get all 'clarke' about this, but tire rubber is, in terms of hardness. very soft but very scratch resistant. You succeeded, though. :-) "one of" not "the" -- -MIKE- "Playing is not something I do at night, it's my function in life" --Elvin Jones (1927-2004) -- http://mikedrums.com ---remove "DOT" ^^^^ to reply |
HVLP question spraying water-based poly
On Nov 27, 1:16*pm, -MIKE- wrote:
On 11/27/10 11:50 AM, Robatoy wrote: On Nov 27, 10:01 am, *wrote: J. Clarke wrote: In , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. *It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. Not to get all 'clarke' about this, but tire rubber is, in terms of hardness. very soft but very scratch resistant. You succeeded, though. * :-) HEY!........ouch! |
HVLP question spraying water-based poly
On 11/27/10 12:22 PM, Robatoy wrote:
On Nov 27, 1:16 pm, wrote: On 11/27/10 11:50 AM, Robatoy wrote: On Nov 27, 10:01 am, wrote: J. Clarke wrote: In , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. Not to get all 'clarke' about this, but tire rubber is, in terms of hardness. very soft but very scratch resistant. You succeeded, though. :-) HEY!........ouch! Happy Thanksgiving! :-p -- -MIKE- "Playing is not something I do at night, it's my function in life" --Elvin Jones (1927-2004) -- http://mikedrums.com ---remove "DOT" ^^^^ to reply |
HVLP question spraying water-based poly
"Robatoy" wrote in message
... On Nov 27, 10:01 am, "dadiOH" wrote: J. Clarke wrote: In article , says... blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. FYI, polycrylic is not polyurethane. It is acrylic and urethane is *MUCH* harder and therefore scratch resistant. Don't assume that harder means more scratch resistant. Scratch resistance is one of the defining characteristics of hardness. Not to get all 'clarke' about this, but tire rubber is, in terms of hardness. very soft but very scratch resistant. Hmm. I'll have to remember that the next time my wife scrubs a curb. {:-) Max |
HVLP question spraying water-based poly
|
HVLP question spraying water-based poly
Robatoy writes:
On Nov 24, 10:25Â*pm, blueman wrote: As a newbie to HVLP, I have encountered the following problem... I am spraying Minwax (water-based) Polycrylic semi-gloss polyurethane. Although the spray seems to atomize well, it seems that unless I put on a fairly heavy coat that it deposits in discrete though very small droplets resulting in a somewhat rough surface. i.e. - the spray doesn't seem to coalesce into a uniform coat unless I spray it on pretty thick. It's almost if some type of surface tension is causing the spray to coalesce together rather than completely and uniformly wetting the surface. When I move the gun slower to let more finish deposit, I do get a uniform sheen that completely 'wets' the surface (however this only works when the surface is horizontal because otherwise it would run). - Is this normal or am I doing something wrong? - If so what are the likely causes and corrections? Note: I am using the low cost but surprisingly well reviewed Harbor Freight #66222 (purple) gun. My 8 gallon compressor seems to have enough reserve to power the gun since it is able to cycle. on and off and the pressure never drops below about 70psi. The surface I am spraying is clean, well-sanded Birch plywood. I have the inlet pressure set at about 30PSI. I have made some (non-exhaustive) attempts to: - Adjust the inlet pressure in the range of 20-40PSI - Adjust the fluid volume - Adjust the spray pattern (more round vs. more oval) - Adjust the distance to the object (from maybe 8 to 16 inches) - Adjust the speed at which I sweep across the object While Minwax claims it hasn't tested and hence can't recommend polycrylic for spraying, others have had good results with it. Also, it seems to be of fairly high viscosity and hence seems to spray well. Thanks I have sprayed the same product with a 2.0 tip on an HVLP gravity feed gun at 45 psi inlet pressure. Medium fan. It works a lot better in a cooler environment. Ahhh my HF gun comes with a 1.4 tip... and as I am just now learning that may make it come out to thin though I'm not sure I understand the mechanics of it. So perhaps that is part of the problem... |
HVLP question spraying water-based poly
"J. Clarke" writes:
In article 8a91b6cf-4e93-4e68-a62f- , says... To get a good, comprehensive answers to your questions, it would be easier for you to simply search this group. The subject of HVLP spraying of water borne materials has been discussed completely several times. Any time you have spraying errors you can have a *multitude* of problems that will generate poor results. Some mimic others, so it is best to get a list of common spraying problems and their diagnosis and begin from there with your own equipment. I spent a lot of time writing out the way to properly set up your gun for spraying a long while back, and I was contacted by more than a few that thought the info I put out was helpful. It might be to you as well. FWIW, I think Rob may be on to something. MOST guns (not all) that come with one tip use a 1.4 to 1.7 mm tip. If you are in that range, it might not be large enough to spray your finish without thinning. If you didn't get another tip with the gun (the 2mm is intended for unthinned latex), try thinning your material about 10% with distilled water, then shooting it. I would also suggest that you find a good book(s) on spray technique. There are a lot of good ones out there, and they can help you troubleshoot your problems. Some of those books will help you realize that there are too many variables to troubleshoot ACCURATELY without a ton of info. They may also be able to help you figure out what you are doing wrong as well. Plan on investing some time and money in learning the spray process. It is no different from any other part of learning a craft, but it seems to be the biggest enemy of wood workers as they feel like it is something that they can learn from osmosis. You can spray material out of a gun by simply hooking it up. But to shoot a well laid, consistent finish is something that takes time, practice, and above all, patience. Note that getting larger tips for the HF gun may be problematical--I tried to get a larger one for mine and the gun had been discontinued as had the tips. They may be available for the replacement model. While the HF purple gun is fine _if_ out of the box it does what you need, I've found that tcpglobal has what appears to be the same gun for not a lot more money and they have a wide range of tips available, as well as repair kits and accessories. Their tips work on _my_ HF purple gun but mine isn't the current model. - Do you know what model you have? - What would I have to check to determine compatibility? (beyond thread diameter and pitch) Note--assume that the regulator that comes with the gun is dead, not just with TCPglobal but HF as well--I've gotten one good one out of four guns purchased. Well the regulator "seems" to work in that at least I can dial up different pressures... Were yours *totally* broken or just inaccurate? (i.e. did you have to check against a pressure gauge to determine whether or not it was working or could you just tell by the dial) If the tip is too small then you pretty much have to thin. Ahhh well I have the stock 1.4 tip so perhaps that is the problem... |
HVLP question spraying water-based poly
Mike - I just want to thank you for your incredibly helpful inline
responses. This is not to imply that the other responders weren't also amazingly helpful and teachable. Just that your answers were so precise and to the point that I felt the need to comment... |
HVLP question spraying water-based poly
Robatoy writes:
On Nov 25, 3:46Â*am, " wrote: FWIW, I think Rob may be on to something. Â*MOST guns (not all) that come with one tip use a 1.4 to 1.7 mm tip. Â*If you are in that range, it might not be large enough to spray your finish without thinning. If you didn't get another tip with the gun (the 2mm is intended for unthinned latex), try thinning your material about 10% with distilled water, then shooting it. I bought that 2.0 gravity gun specifically for squirting Sikkens 3+1 primer. An automotive product that just works wonders on MDF's edges and routed profiles. The build is insane, the sandability fantastic. (For some reason my spellchecker balks at sandability...oh well.) That stuff is so thick, it needs a tip that large. It's an Iwata LPH440-201. I took it, all nice and clean to my buddy's booth as I needed to blow some thanes on a few sheets of luan. I checked the Polycryl with a viscosity cup and looked almost too thin for the 2.0 (IMHO, a 1.8 would have done it too). I wasn't about to dirty up his pot-fed equipment. (Waterbased snot in HIS guns? He would have murderized me.) It went on so nice even though I was using a LOT of air to blow that snot apart. I have revisited the same spray schedule since with the same results.... and if it works, don't mess with it. I think you have diagnosed it spot on. I didn't (and still don't fully) understand how tip size works but you have pointed me in the right direction. I think the problem is finding other than non-stock 1.4 tip sizes for this gun, though I have seen at least two alternative suggestions: 1. Buy a spare 1.4 tip and drill out the hole a little 2. Find a tip from other companies that fits... Thanks for the pointers and experience! |
HVLP question spraying water-based poly
Robatoy writes:
On Nov 25, 3:46Â*am, " wrote: FWIW, I think Rob may be on to something. Â*MOST guns (not all) that come with one tip use a 1.4 to 1.7 mm tip. Â*If you are in that range, it might not be large enough to spray your finish without thinning. If you didn't get another tip with the gun (the 2mm is intended for unthinned latex), try thinning your material about 10% with distilled water, then shooting it. I bought that 2.0 gravity gun specifically for squirting Sikkens 3+1 primer. An automotive product that just works wonders on MDF's edges and routed profiles. The build is insane, the sandability fantastic. (For some reason my spellchecker balks at sandability...oh well.) That stuff is so thick, it needs a tip that large. It's an Iwata LPH440-201. I took it, all nice and clean to my buddy's booth as I needed to blow some thanes on a few sheets of luan. I checked the Polycryl with a viscosity cup and looked almost too thin for the 2.0 (IMHO, a 1.8 would have done it too). I wasn't about to dirty up his pot-fed equipment. (Waterbased snot in HIS guns? He would have murderized me.) It went on so nice even though I was using a LOT of air to blow that snot apart. I have revisited the same spray schedule since with the same results.... and if it works, don't mess with it. OK - now that I am pretty convinced that I need more than my stock 1.4 tip, as a newbie and a hobbyist, what would be the most useful other tips to order assuming I might want to spray latex paint, lacquer, shellac, oil-based poly, primer (for wood)? Specifically, before I start shelling out loads of money for all possible sizes what 1 or 2 additional tips would give me a good range of coverage assuming I already have the 1.4? Thanks |
HVLP question spraying water-based poly
blueman wrote:
Ahhh my HF gun comes with a 1.4 tip... and as I am just now learning that may make it come out to thin though I'm not sure I understand the mechanics of it. So perhaps that is part of the problem... Nope - the tip does not make it come out thinner - smaller tips require thinner material. For a 1.4mm tip you would want quite a thin material, or it will not spray it well. Start adding more reducer (water for water bases materials) and test shoot until you get a good pattern. Increment the amount of reducer by 10% or so until you get t good, shootable mixture. Keep note of how much reducer you are adding so that when you get to the point where it's spraying well, you can reproduce that ratio of reducer to material later on. -- -Mike- |
HVLP question spraying water-based poly
blueman wrote:
Specifically, before I start shelling out loads of money for all possible sizes what 1 or 2 additional tips would give me a good range of coverage assuming I already have the 1.4? I don't know what sizes are available for that gun, but anything in the 1.7-2.0mm range should be just fine. No need to buy more than one. You really don't need a collection of them for "every conceivable" application. -- -Mike- |
HVLP question spraying water-based poly
"Mike Marlow" writes:
blueman wrote: Ahhh my HF gun comes with a 1.4 tip... and as I am just now learning that may make it come out to thin though I'm not sure I understand the mechanics of it. So perhaps that is part of the problem... Nope - the tip does not make it come out thinner - smaller tips require thinner material. For a 1.4mm tip you would want quite a thin material, or it will not spray it well. Start adding more reducer (water for water bases materials) and test shoot until you get a good pattern. Increment the amount of reducer by 10% or so until you get t good, shootable mixture. Keep note of how much reducer you are adding so that when you get to the point where it's spraying well, you can reproduce that ratio of reducer to material later on. Does one that get into a bit of a paradox: - Too thick means it doesn't atomize and coalesce properly - Too thin means it sprays nicely but runs and sages unless coat is applied thinly Which would seem to mean that if I use my current tip, but thin then I will have to put on more thinner coats. While getting a wider tip would spare the need for adding reducer and would allow me to apply a relatively thicker coat without sagging or running. Am I understanding this tradeoff properly? Also, would having the right size tip and/or right viscosity typically allow me to lower the HVLP inlet pressure (I now have it cranked up to about 30psi but ideally, I know I could or should go a lot lower...). |
HVLP question spraying water-based poly
blueman wrote:
"Mike Marlow" writes: blueman wrote: Ahhh my HF gun comes with a 1.4 tip... and as I am just now learning that may make it come out to thin though I'm not sure I understand the mechanics of it. So perhaps that is part of the problem... Nope - the tip does not make it come out thinner - smaller tips require thinner material. For a 1.4mm tip you would want quite a thin material, or it will not spray it well. Start adding more reducer (water for water bases materials) and test shoot until you get a good pattern. Increment the amount of reducer by 10% or so until you get t good, shootable mixture. Keep note of how much reducer you are adding so that when you get to the point where it's spraying well, you can reproduce that ratio of reducer to material later on. Does one that get into a bit of a paradox: - Too thick means it doesn't atomize and coalesce properly - Too thin means it sprays nicely but runs and sages unless coat is applied thinly I tried to correct this misunderstanding of yours in a past post. You are too worried about how thick you are spraying it on. Don't be. Spray it on like a layer of plastic you are stretching across the base material. If it takes 3 coats - it takes 3 coats. If it takes 10 coats, it takes 10 coats. Follow the manufacturer's directions for overcoats and just keep building it up as necessary. The only thing you need to think about is imagining that you are stretching a piece of plastic over the surface you are painting, and making your spray application do that. If you are getting runs and sags (and don't worry about that - I *still* shoot some once in a while), then you're moving too slowly. Practice on scrap. Hear me? Practice on scrap. Which would seem to mean that if I use my current tip, but thin then I will have to put on more thinner coats. Yup. You got it. No problem with doing it that way. While getting a wider tip would spare the need for adding reducer and would allow me to apply a relatively thicker coat without sagging or running. And bring about other problems like shrinkage. There is no short cut to doing it right. It sounds like you're looking for the one shot finish, and that does not exist. Yes - a larger tip will put more down at once, but then drying times extend, shrinkage enters into the picture, and if you do run - you really run... or sag. It's more about technique than it is about tip sizes. You really have to practice with that gun on scrap and get the feel for it. I just shot a bunch of primer through a detail gun. Would not lay on a heavy build coat with the tip that I had. So... had to reduce the mixture and shoot slower in order to get a good we coverage. Oh well. That's what you do. If you are looking for the perfect tip for the perfect spray material, on the perfect target - you're going to be very disappointed. Mix up something your gun will shoot and.... practice. Am I understanding this tradeoff properly? Yes, but my fear (and I may be reading you wrong...) is that you're looking for a silver bullet. Spray painting is all about adapting to the situation. Humidity, temperature, viscosity, and a lot of other factors, enter in on every single spray job. That's why I'm so adamant about pushing your to experiment, learn your gun, and practice. You can overcome any issue with spraying if you understand your gun. Also, would having the right size tip and/or right viscosity typically allow me to lower the HVLP inlet pressure (I now have it cranked up to about 30psi but ideally, I know I could or should go a lot lower...). Yes. The first thing you have to do is get the reduction such that your gun can shoot it. So - reducing it to the point where you can get your pressure down is very important. You don't really have HVLP anymore if you're shooting at those high pressures. You're blasting more material into the air than you realize. Might just as well grab a decent siphon gun and have at it. So, once you get the reduction right - you know what I'm going to say... -- -Mike- |
HVLP question spraying water-based poly
"Mike Marlow" writes:
blueman wrote: Specifically, before I start shelling out loads of money for all possible sizes what 1 or 2 additional tips would give me a good range of coverage assuming I already have the 1.4? I don't know what sizes are available for that gun, but anything in the 1.7-2.0mm range should be just fine. No need to buy more than one. You really don't need a collection of them for "every conceivable" application. Not to be too anal... but if in the future I hope to also shoot semi-gloss Benjamin Moore Latex, would I be better off getting a 1.8 or a 2.0 (or is the difference really too small to worry about...) |
| All times are GMT +1. The time now is 04:17 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter