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WB Coatings - successive layer orange peel texture10/23
I've been spraying clear and pigmented SW Kem Aqua+ for 2 years now on various casework/kitchens. My typical pigmented schedule is 1x coat of SW KA+ surfacer followed by 2x pigmented topcoats. I am using a good-quality Lemmer PP setup with a Lemmer conventional 1.4mm tip gun @ 42-45psi on the gun and 10psi fluid pressure. My surfacer coat lays fine. I apply my first topcoat for build at recommended mil thickness and it lays down wet, looks good, and dries good. My second coat is applied exactly the same way, looks good, but most always has a very "large texture" very slight orange peel texture to it. It is more pronounced in reflected light. The first topcoat always looks better than the second, it just lacks any build. The problem only becomes more pronounced the more topcoats I add to the system… as in, if I have to reshoot a door to repair a finish defect, the 3rd topcoat has this orange peel texture more pronounced. It has happened to me with the SW KA+ as well as MLC’s Agualente and Magnamax H2O.
My wife can see it when I point it out but I haven't had any clients complain. I'd love to get to the bottom of what causes it. I’ve tried several guns, tried higher and lower atomizing pressure, tried heavier wet mil applications, etc. Anyone have any thoughts?
Yep, been liv\ing with this same problem forever. I don't have a good solution. Sometimes it seems to work fine, so I've always suspected that time between coats had something to do with it. Maddening when it happens.
The joys of waterborne.... since your already using sherwin products go ahead and switch over to the sayerlack side of sherwin for waterborne.... we tried for years to get the kem-aqua to behave predictably but never really had success.... We only use waterborne when forced to for specific green jobs... otherwise we spray the good stuff! when i do have to go waterborne the sayerlack does perform a little better for us. The trick is reduction and retarding... make sure your reducing with distilled water only at 10-20%.... we also retard with propylene glycol at 10%... Reducing and retarding these this way makes it lay out a ton smoother... Water always looks like crap until it shrinks back an hour later..
they dont like to lay without a full sanding, you have to have a complete scratch to flow over the previous coat
Id argure that the water tends to look better the next day ;-). The shrink back is definitely better with time.
I find with water de-nibbing with a much higher grid than you'd normally use makes a huge difference in how the second coat lays out.
Ever more, the commercial jobs we are bidding spec' water so o'pyning(sp) over "the good stuff" seems a lost cause. If we want the job, and the paycheck, you just put up or shut up.
Thanks for the responses folks.
Shane: are you suggesting to retard at 2 parts, reduce at 1 part, and have 7 parts waterborne finish? That sounds very runny... I did try and source Sayerlack, but it had to come to me through a SW product finishes department store (4 hours away) and it just isn't going to work for color matches etc. I would still like to try some of the clear though for drawer boxes and the like.
Jon: I do scuff sand between coats with 320gr. I was using 220gr but could see some of the scratches under the topcoat. What are others using for their scuff coat?
Mark: higher grit for scuff sanding as in go up past 320gr (600gr) or down to 220/180gr?
I do agree that the finish most ALWAYS looks better the next day. My rep keeps pushing me onto solvent borne solutions from MLC... but I like the water stuff, and my spray booth is not explosion-proof. I have made it work, and as said no complaints from customers. I'm just always trying to improve both my spray and finishing techniques - hence why I'd like to solve the orange peel look. In a way, it makes me feel slightly better that others are suffering too lol.
First thing I would try is a bigger tip, 1.4 is more for an automotive finish. A problem with most guns that are decent quality , but not high end, and are available all over the place, even places like harbour freight, is they are built and sold with the person who is going to paint their vehicle in mind.
Your setup might be off.
You are putting a thick finish thru too small of a tip with not enough pressure.
I set the tank pressure with the beer piss method. Start at 10 and work your way up towards a max of 20(thick primer). When the stream has a nice long arcing stream like a beer piss you are golden
I could never get KA+ to lay out well, even on the first coat, until I started adding extender/retarder to it. 3% of GF's Extender and it was a whole new world. I actually enjoyed spraying it after that. FWIW, I was using a 1.3 mm N/N set with 5 psi on the PPS cup and 29 psi inlet pressure.
Also, Lenmar's Duralaq-WB lays out beautifully for me straight from the can.
No offense taken Scott. I guess I'm just not good enough to spray uniform coats w/o runs or pooling at inside corners with a larger N/N and higher flow.