Paint & Reducer Ratio

[JackIIA]

I was painting today (epoxy, then acrylic primer...next will be top coat).

But at first, I was getting globs of paint out the HVLP spray gun. At first I thought it was an air pressure issue (too little), then obviously figured it must be the paint flow rate (too much).

After quite a bit of fooling around, I determined the paint needed a lot of reducer...as in 5:4 (paint to reducer) to flow smoothly and finely.

I've heard of people using 1:1 ratios for paint and reducer, but that's not what I've been told by paint suppliers is normal. Not trying to be cheap, but wanted to see what others have done for their trucks. I was expecting something more along the lines of 5:1, but it was complete crap when I shot it that way. So, I basically ended up spraying paint that was almost the consistency of water - very thin. 1 Coat epoxy, 4 coats acrylic primer.

I'm using quality stuff (PPG). The gun is nothing special - it's Harbor Freight with a 1.8mm tip, but it seems OK.


So, is it "normal" to use this high a ratio of reducer? When I shoot the top coat, same deal? Whatever works works?

[bkreutz]

Every paint has it's own ratio marked on the can. The ratio stays the same but the speed of the reducer is adjusted for temperature. Some minor ratio adjustment can be done for special conditions. I've never had good luck with cheap guns and 1.8 sound pretty large for primer, I usually use a 1.6. HTH

[JackIIA]

Gale - I was wondering if it was the gun, but I figured no, it must be something else. Surely Harbor Freight wouldn't sell something unproven ;).

What happens in the event of TOO much reducer? My initial thought is that the impact is simply a thinner coating. However, is the other impact extending cure time? Which I'd guess could eventually cause lifting of subsequent coats for instance.


- Looks Like I Found My Answer: The risk is blistering. I guess we'll see.

[solihull109]

You mentioned you're using an HVLP gun, but what pressure are you set at the trigger? Too much pressure will give a different atomization , and the overall effect.

a 1.8 tip seems a bit big for what you're spraying, if you're using PPG products, you can contact the rep at the store you purchased from and he'll guide you along.
Your reducer ration seems off too, which PPG products are you using, ( the numbers)?

[JackIIA]

You mentioned you're using an HVLP gun, but what pressure are you set at the trigger? Too much pressure will give a different atomization , and the overall effect.

I ended up with a range of pressures, basically between 25 - 35 psi to get the right cap pressure. confirmed that with the PPG shop.


a 1.8 tip seems a bit big for what you're spraying, if you're using PPG products, you can contact the rep at the store you purchased from and he'll guide you along.


the 1.8 tip was what they recommended. the actual paint specs called for 1.6. i tend to think the issue is indeed the gun rather than the tip. i tried quite a few settings to get a good spray pattern, without much luck.

the effect was similar with the 1.4 setup in the same gun and top coats.


Your reducer ration seems off too, which PPG products are you using, ( the numbers)?

the reducer was off. far too much. i ended up really cranking the heat. luckily most of the primer i sprayed was without reducer. only last light coats. the ppg folks said to extend cure time and temp, which i did. DPLF, K36 and DCC.

i shot the final coat today. i'm definitely replacing the gun. i don't recommend the harbor freight HVLPs. Normally, I'd say "duh" of course not. But there were quite afew folks chiming in online about their HF guns and that they were happy with the results.

Anyone with experience with a GOOD gun for around $100. I'd expect that would be enough to get something that was a non-pro unit that will still give a reasonable finish?