Plastic Liner Bags for HVLP?

[WoodWrangler]

The question may seem so simple that it's silly, but it's a sign of my ignorance on the subject...

I have a Fuji Q4 HVLP system and some plastic liners for the fluid cup on the gun. In theory, you put this in the cup and put the finish in it so simplify cleanup. However, I've yet to do it ... probably because I'm not sure about how this really works and if it would mess up the gun. The cup is pressurized, I believe, and as the liquid is drawn out won't the plastic liner "suffocate" the system?

Am I missing something? Is this of no concern? Should I use the liners?

[woodlaker2]

Probably works much like those plastic bag type baby bottles. The bag just collapses gradually as the liquid is used up. Should be fine.

[Travis Porter]

I have never used them, and really don't see the need. Sure it will keep the cup clean, but you are still going to have to remove the needle, cap, etc and clean that along with the flow tube so does it really help you out?
Since the air in the cup is under pressure I don't believe it will "suck up" like one of those burpless playtex bottles.For an oil based finish, maybe it would be a help, but I don't think it would do much for waterbased.
Maybe it work better, I just don't see it. If you try it and find it does, I would be interested in hearing it.

JMTCW.

[thrytis]

I tried one of the HF liners for the HF gun once. It ended up making a poor seal between the cup and the gun and leaking the finish all over. It turned out to be more work cleaning with the bag than without it!

[WoodWrangler]

I think I've heard enough...

I've never had a problem cleaning the gun... so I guess there just isn't enough value. Maybe for paint, but nothing else.