Technique Question- Thinning WB

[Mark Hulette]

Just curious of the step-by-step procedure of how the experienced finishers out on the Creek thin WB material to get a consistent "batch" for each coat. I'm specifically referring to a sprayed application but other methods are welcome.

Thanks!

[Larry Fox]

I can't tell you how the experienced guys do it but I can tell you how I do it. Depending on the size of the job I try and project how much I will need to do it all and add 10%. I then choose an appropriate container that I think will hold enough plus about 25%. Depending on the amount that I need to thin, I will then choose a container which will hold it all plus some. If I am thinning 5% I add 20 "scoops" of material and make a mark on a piece of paper. I will add as many 20-scoop batches of material as I need making a mark for each one. When I am done I will add one scoop of thinner for every mark on the paper. Similar logic holds for other thinning ratios.

I don't add the thinner until the end in case I loose count and have to start over. DAMHIKT

I am SURE there are easier and more accurate ways but this works for me.

One thing that I always do is count aloud - seems to help me.

From this point you know you have a batch that has been thinned about 5% and you can tweek it from there as needed.

Hope it helps (and that it addresses your question). . .

Larry

[Howard Acheson]

Just curious of the step-by-step procedure of how the experienced finishers out on the Creek thin WB material to get a consistent "batch" for each coat. I'm specifically referring to a sprayed application but other methods are welcome.

Thanks!

Before you do any thinning of waterborne finish, check the label. Never thin waterborne more than stated on the label. If the label does not specify thinning, don't unless you contact the manufacturer.

Water is NOT a thinner for waterborne finish. The reason for calling them "waterborne" is that the chemicals are kept apart by the water. When the water evaporates, it allows the other chemicals to come into contact causing a coelescing or "melting together". The coelescing then forms into a film of acrylic plastic. If you add too much water, the chemicals will not come into contact when the water dries and the coelescing will not occur or only occur irregularly.

So only thin if you have specific directions to do so. If you are spraying use the correct cap and needle. Don't thin.

[Larry Fox]

Howard, what are they thinned with if not water? Advise from Target Coatings is to thin their products with water if required.

[Howard Acheson]

Most waterbornes are already quite thin and should be just fine for spraying. As I said in my prior post, don't thin unless advised by either the label or the manufacturer. The amount of thinning, if allowed, is determined by the manufacturer. There is no general rule.

IMO, it's alway best to set up your equipment to spray the product at full strength.

[Bob Reda]

I was also told by Target to thin with water. I find that their topcoat is thin enough, the only thing I ever thin a little with water is their sealer, its a little thicker than their topcaot. Great stuff by the way.

Bob

[Larry Fox]

Howard, I agree with your second post. However, in your first post you say that water is NOT a thinner for WB finishes. I guess I am asking - if one needs to thin what would you thin with if not water. Am I misunderstanding something?

Rob, I agree but I do thin their Conversion Varnish by about 5% and find that I get a much better finish off the gun with a ~2mil wet film thickness. Their USL and WB shellac products are thin enough out of the can for my setup. I am using a 3-stage Fuji HVLP.

[Jim Becker]

I've not found it necessary to thin the water borne finishes I've used with my gun, including TC USL/PSL, Fuhr International 9100 and Behr water borne poly. But yes, check with the manufacturer and don't thin more than absolutely necessary. Too much and you've compromised your finish.

[Steve Schoene]

The solvent in waterborne paint is ethyl glycol since it will dissolve the cured material. The resin is dissolved in this, not water. Water just holds little packets of resin/solvent apart so the emulsion can be brushed or sprayed. In that sense, water is a thinner for waterborne finishes, I suppose, but it should not be added to the producted formulated by the manufacturer except within the very small limits explicitly specified by the manufacturer. It does not work like naptha or mineral spirits in an oil based varnish where you can add thinner in any amount. Too much extra water and the finish may fail completely.

Also, unlike the situation with oil based varnishes, there is no incentive for manufacturers to use too little water in the product they sell. It's the cheapest ingredient and isn't a regulated VOC. Therefore, you can expect the formula to have sufficient water--especially since the manufacturer can sell the water at the price of varnish.

[Larry Fox]

Thanks Steve - the explanation makes sense. Helps understand WB a bit better.