Paint viscosity

[eil]

You've bought your paint, lacquer and got the tech sheet where it states eg mixing ratio 2 : 1, add if necessary 10% thinner.
Then it will say Application viscosity 18 sec.
What if the paint is still too thick, do you add more thinner or ramp up the pressure for it to atomise properly.

 

[pedrobedro]

I usually add more thinners using my gravity feed gun anyway as I only run it at 40psi. Are you setting the regulator pressure with the trigger pulled ?

 

[the snooper]

the spec sheet usually states gun pressure aswell what paint is it also it should state what viscosity size cup is used after mix as per above if the paint seems too thick you have something wrong

 

[eil]

I noticed that they give a "spray at" pressures as well which has about a Bar difference, I have also noticed that with HVLP guns they say 2Bar at the gun no more, now JK says most sprayers overdrive their guns and was wondering what is peoples opinion to over thinning or upping the pressure to get the right atomisation of the paint was. Only asking as the lacquer I used recently needed more thinning to get the viscosity right, and it covered OK like that, that is with more thinners as opposed to upping the pressure as I couldn't really get more pressure at the gun really.

 

[jaykay]

sounds like you have found a happy medium,go with it.
dont change mix/setting all at once or you'll never know what was the adjustment that did the job.
lots of things come in to play,now it's colder paint/lacs will be thicker.
do you use a vis.cup.also there are differant cups that give a diff reading.
i personally dont use them anymore.just go by what i know will work.

 

[eil]

I was just wondering if it was not a good thing to over thin with 2K, as I remember with celly you could put more thinner coats on to cover instead of two thicker as long as it flashed off in between.

 

[eil]

Yes I did for the first time ever, bought the devilbiss ford no4 viscosity cup

 

[jaykay]

you say above that spec says add 10% thinners,have you done that and still need it thinner??if so add more to get what you want.
i found going by vis.cups it was thicker then what i wanted it.

 

[eil]

Yes Jay thats how I found that it was thicker and needed thinning more to get the 18sec to spray at. it worked ok.

 

[jaykay]

great,its just knowing when to bend the rules.
get on to the paint companies,and they just say spec sheets are just a guide.

 

[eil]

Thats experience for you Jay, you do it daily as against my yearly, so you instinctively know what you need it at as opposed to myself who has bouts of memory loss as well

 

[jaykay]

lol that happens to us all.
i dont spray every day now(semi retired) just do the jobs i want to do.

 

[Drew 13.]

Hi, I new to the site and hope it is ok to ask questions. So do you set the air pressure with the trigger pulled on the gun?

 

[eil]

Yes thats how I have been doing it, got one of them little regs on the inlet to the gun.

 

[Drew 13.]

That answers my question, thanks. I've got a HVLP gun and the pressure is that low when you pull the trigger it just spits. Luckly only used it for priming up to now.

 

[mike os]

pressure & viscosity are largely a matter of personal choice... find what works for you without over thinning the paint & go with it.

 

[eil]

That answers my question, thanks. I've got a HVLP gun and the pressure is that low when you pull the trigger it just spits. Luckly only used it for priming up to now.

What size and length of airline are you using, as well as fittings, regulator/water separator.

 

[brightspark]

pressure & viscosity are largely a matter of personal choice... find what works for you without over thinning the paint & go with it.

thats what i do always have i always do a test piece 1st on a 1 gal can or a 5 gal drum with all paints

 

[mike os]

I think it helps if you started with celly when it was the only choice & the only real choice in guns was what cap size you were using..... must have been spraying for 15years before I even heard of some new fangled device called a viscosity cup

 

[jaykay]

viscosity cups? for checking your tea is strong enough,right????
seat of pants every time.
dont be fooled there are a few differant vis/cups.and all measure differantly.