Global Scale Modeller

Twokidsnosleep wrote: Sun Feb 14, 2021 5:45 pm Never leave any lacquer thinner cleaner in the airbrush as residue will kill the seals
I always spray out with my acrylic airbrush cleaner as a final step even if it is a lacquer designated airbrush
Then I prime the airbrush and test it’s spray pattern with the paint appropriate diluent immediately before adding the paint

Just my $.02

Kevthemodeller wrote: Wed Feb 17, 2021 11:05 pm All very odd and they appear to have changed colour

I've had the same seals in my two H&S since I bought them one is about 4 yes old the other 2. I use both water/alcohol based acrylics, lacquers and metal finish paint. I use Tamiya, Mr Hobby, AK Extreme, Cellulose thinners and Mr Tool cleaner, I always back flush and leave a small amount of cleaner in the cup. I only strip the brush after completing a kit and use Badger needle juice for lub.

I've never had any issues with mine

digger303 wrote: Wed Feb 17, 2021 11:21 pm I'v used your method many times except I cannot always leave a small amount of cleaner in the cup. If left for extended periods in just evaporates in this climate. So your comments of not changing the seal in 4 yrs perplex me given my experience. The seals turning green is perhaps just a paint stain. Even when new seal are installed the needle slips through the seal almost like they have made the hole too big even with 3 seals . I'm going to my favorite industrial seal supplier tomorrow to see if he can supply a better seal. He was most helpful the last time I needed viton o rings for my Paarsch.

Kevthemodeller wrote: Thu Feb 18, 2021 10:46 am

digger303 wrote: Wed Feb 17, 2021 11:21 pm I'v used your method many times except I cannot always leave a small amount of cleaner in the cup. If left for extended periods in just evaporates in this climate. So your comments of not changing the seal in 4 yrs perplex me given my experience. The seals turning green is perhaps just a paint stain. Even when new seal are installed the needle slips through the seal almost like they have made the hole too big even with 3 seals . I'm going to my favorite industrial seal supplier tomorrow to see if he can supply a better seal. He was most helpful the last time I needed viton o rings for my Paarsch.

As far as I'm aware and in my experience when when PTFE comes into contact with solvents at worst they expand and soften they don't shrink. Those solvents have been way, way more volatile than any standard cleaner/thinner we'd be using, which is why H&S use them. If anything they are so robust they wear like bearings i.e. the needle enlarges the hole, which yours appear to suffered. This is easily sorted by slight adjustment (tightening) of the packing screw. Have you tried this? It can be done with a quality standard screwdriver but be careful the screw is brass and soft, H&S do a special tool.

The latter I had to do a few times when I used Iwata super lub, which dries out almost over night and forms a sticky paste, horrible stuff. Since using Bager needle juice no such problems, one application last many cleans. But even that was after a lot of use, PTFE is self lubing it's one of its properties as is solvent resistance.

I'm also very puzzled by the change in colour, again PTFE isn't porous.

I'd be inclined to contact H&S and see what they have to say, something isn't right and I'm sure they'd like to know or already do know.

Kevthemodeller wrote: Thu Feb 18, 2021 11:44 am All very odd mate.

The seal on the back of the nozzle is the same stuff, I often just leave my spare .2/4 in Mr Tool, Mr Hobby lacquer thinners both types and at times cellulose thinners for days at a time, still using same seals never changed.

Is there not an main dealer or importer of H&S in Oz?

Try contacting Paul at Modelling Tools

He sells and deals with H&S and he's a very helpful chap.

onemac wrote: Fri Feb 19, 2021 10:22 am Wow, that's a fair mess of those seals. I suspect a bad batch as they should be resistant to lacquers (paint or thinners). Contact H&S about this and see what they say.

I use lacquer thinner (the cheap rough stuff) to clean all my airbrushes but you always, always have to clean and backflush with a good airbrush cleaner afterwards (Ultimate) to neutralise the lacquer thinner. Then I add a few drops of Ultimate thinner and spray some through until the next use. Remember to flush the thinner out before you use the brush and just as a precaution spray some good (Tamiya or MLT) lacquer thinner through if you're going to use lacquer paints. No need of course if you're using acrylics because you've already sprayed through the thinner sitting in the brush and then once a month a deep clean using Regdab to lube the needle/seals and you're good to go.

Let us know how you get on with these new seals and fingers crossed it doesn't happen again.