Paint dilution nightmare

[tim]

Help please!!

I have a whole bunch of cabinets that I'm running behind on (entirely my fault - too lazy over Xmas ) and was about to start priming them this evening. I haven't sprayed MDF primer with my (Newish) Fuji system yet but it is Dulux Trade (waterbased) QD MDF primer which is suitable for spraying and according to the pdf doc on the trade site probably needs thinning by 10%. However to get it to run throught the viscosity cup at the rate set by the table in the Fuji manual it needs to be diluted by 50%. I don't know which cup type it is but it is the one that came with the Fuji.

I will get onto Dulux tomorrow (and Fuji) but in the meantime can anyone help. At that level of dilution the coverage is poor (very wet) plus I'm getting a lot more overspray than I would expect.

I am pretty confident that it is down to user error :shock: and not equipment or materials so can anyone help the late night spraying muppet please!!!

As always at this stage I promise that on the next job I will start earlier and set a better deadline (never happens though).
:wink:
Cheers

Tim

 

[houtslager]

sounds like your using the standard needle and air cap , for most primers and heavy latex finishes that are water based one need to use the no 3 needle and cap.{ appollo 800 }
So, go out and get these asap and then you 'll have it all sprayed in a jiffy

 

[Chris Knight]

Tim,

Wot HS said (change nozzle/needle) plus the observation that most water-borne clear finishes (lacquers) cannot stand dilution above 5 or 10% (the suspension just falls apart). I would be surprised if the stuff you are using is a lot different in this respect.

 

[tim]

Thanks I'm happy to try that but one (naive) question:

The standard cap is 1.4 mm. The No. 3 is 1.0mm, I would have thought that a larger aperture rather than a smaller one would have been better.

I don't disbelieve you, I just don't understand the principle very well.

Thanks

Tim

 

[tim]

One thing I forgot to add to the post -irrespective of the cap size -what do I do about the viscosity because that will still mean the 50% or so dilution to get it to run and I agree fully with you Chris about the integrity of the suspension. Should I ignore it and just dilute by 10% or so with the 1mm aircap?

Thanks

T

 

[Chris Knight]

Tim,
I don't own a Fuji ( I have a turbine system (Wagner 4 stage) but their manual suggests the number 4 nozzle/needle with a 4 stage turbine is preferred for latex emulsions (http://www.fujispray.com/technical.htm)

Note that latex is the American term for water-borne emulsions - I have no idea if there is actually latex in them.

I don't know how many stages your turbine has but it may be underpowered looking at the Fuji info. We live a bit far apart but you are welcome to borrow my unit if you wish and could face a long drive.

I would ignore the viscosity cup for the moment and check that the stuff can be diluted carefully to a point where it runs freely off a stirring rod and maintain its integrity. If it cannot be diluted to this level then I question whether the stuff is designed for spraying with HVLP or a conventional gun for that matter. It may be basically a house paint and designed for use with airless guns which can pump cement if need be.

 

[tim]

Chris,

Spoke to Dulux. They recommend c 30% for this paint for HVLP. My Fuji is 3 stage. I've ordered the No. 3 nozzle (which I'll need anyway for finer stuff), it comes with the No.4 anyway and I'm going to experiment. Thanks for your offer of equipment but you are right its a bit far.

My concerns were based on too much information, too many variables and too little knowledge!!

I'll let you know how I get on.

T

 

[Chris Knight]

Tim,

Good luck!