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Thinning and retarding water based lacquers and coatings

There are a few tips to thinning and retarding water based materials that are common to most all of the water based materials on the market today, knowing these tips can make spraying out water base materials easy fun and most importantly give you the control over the flow of the materials so you  compensate for the varying conditions of your environment.

One of the things to be aware of with water based materials is that they are temperature and humidity sensitive, meaning that on a cold and rainy day it will take forever to dry if left wit out forced air and some heat.

The obvious and wonderful characteristic about water based materials is that you can thin them with water; water is cheap and not explosive.  No one has ever accidentally blown up their shop with a bucket of water.  That being said   you can overthin with water and that can create a mess.

Before we get into percentages and how much you should thin, one thing you should know is that the warmer the materials are, the thinner they will be. This is true of both water base and solvent materials.   Heating pads, bucket heaters and in line material heaters are all things that you can implement.  Inline materials heaters are pricey and not something that are too common here in Southern California  but can be used. More commonly and more practically you can just keep your buckets off the concrete floor or move the bucket in to the office of the shop overnight if it’s cold out. Warming up water base is easier and safer than warming up the solvent materials and in fact with some water base materials you can even warm  them up in the microwave machine, a little impractical but not impossible.  For every 10 degrees you heat the material you will reduce the Viscosity by 10% .  And that is a good thing to know because you can reduce your labor by putting on a thicker coat save our self the labor of having to put on another one of or two more sometimes

Now onto the more practical, the first thing that you should do is adjust your equipment to the material in other words if you have been spraying lacquer with an extra fine airless it’s probably going to be too small an orifice for the water base; you don’t want to overthin it so that you can get it out of  your gun but rather get a bigger tip. Generally a 1.7 mm tip in a cup gun and or something no smaller than a .014 in an airless and that would be the smallest I recommend 1.8 or a 2.0mm tip and needle for a cup or gravity gun.

When you do need to thin the materials down I start out with about 5% water and see how it’s coming out of the gun and laying down, with water based a good heavy coat is what you want if it looks a little blue you are doing good. You want it heavy enough to flow out but obviously not so heavy that  it is running.

Ok the next thing is getting it to flow out and lay down smoothly if it has any orange peel to it then you need some retarder. I generally add the retarder whether I need it or not as I like that fact that it flows out better, this might not be true of all water bases but the ones I have used it just seems to work better with the proper amount  of retarder.

Glycol ether is the solvent for retarding water based material you can also use that for retarding regular solvent lacquers   If you use too much your coating will never dry. The other thing to know is that you can add the retarder too fast and “shock” the material. Shocking information, but true. Dump the retarder directly in to your pot and it can cause itto foam up and have an adverse reaction. Some chemicals go together easily and some don’t;  then there are others that are right on the boarder, this in one of those. So the best way to add the retarder is to mix it 50/ 50 with water first and then add that into the water based lacquer while stirring it. Start out with one to two percent of the   50/50 water retarder solution and see if that doesn’t do the trick for you.  You can go as high as about 4%. If you are working with pigmented water base materials then you can go up to 7% .

White and pigmented lacquers require more and will have a tendency to “mud Crack” (Mud cracking is the phenomena whereas the material dries it begins to crack like mud drying out)   if you don’t use the retarder, what is happening is the solvents are drying out of the pigment faster than the pigment is drying and so you need to slow the process down so that they all dry and flow together.

Not all retarders are the same, some companies sell retarders that are a combination of different things, these work well for solvent lacquers but not always for water based materials.  You either want a lacquer retarder that is made and marked for Water based materials OR you have to test them. The way  you test your normal run of the mill retarder to see if it will work in your waterbased system is to mix it  with water. Simple, if it mixes in you’re good If it separates and doesn’t mix in or foams up and looks weird then its not going to work.  There are a few manufactures that have acetone in their retarder which doesn’t mix well with water If you add that to your water based lacquer its trash.

Ok I hope this information is clear and to the point. Use it and let me know what you get. Leave comments on the blog posting for others to see. I have specifically kept this report completely generic so that if you have a product that you are trying out for the first time it is generally best to contact the manufacture and ask them what they recommend, the better companies will spend the time to answer your questions others won’t

 Thanks,

 Greg Saunders
Annex Paint

February 20, 2011 Posted by | CIC Centurion, water based Conversion Varnish, Spray techniques, Water based Lacquers | , , , , , | 2 Comments