Spray guns & airbrushes etc.

[ayjay]

I expect someone on here has some experience of spray guns: if you do I wish to pick your brains.

 

I'm not planning on painting anything, I want to spray ceramic glazes, there is some info on the web about the basic requirements but it's all very patchy and often lacking in detail.

 

What I have gleaned so far is that for an HVLP gun a nozzle size of 1.5 to 2.0 mm is the best option for ceramic glazes.

 

For glazing ceramics, whether with a spray gun or any other method the glaze should be passed through a fine sieve, 100 mesh is a common size for most glazes - the holes in a 100 mesh sieve are 0.152mm. When a glaze is ready for application the consistency is about the same as single cream.

 

I've acquired a nice little compressor with an output of 5.0 cfm, most of the spray guns I can find which will operate with that size of compressor have a nozzle size of up to 0.8mm.

 

So, the question is, if my glaze will pass through a 0.152mm sieve why do I need a 2.0mm nozzle?

 

Second question: I will probably buy an airbrush as well for more detailed stuff (but still ceramics), finding one of those with a 2.0 mm nozzle is not easy, can a smaller nozzle be drilled out to a larger size?

 

 

 

 

 

 

[Newt]

http://community.ceramicartsdaily.org/forum/19-ceramic-arts-daily-forums/ or some other ceramics forum is probably better for this sort of information.

[Si...]

I would think that the ceramic glaze is a lot thicker than what spray paint is, so you would need a larger nozzle to allow the same amount of fluid through to give a good even coating.

 

eg: In automotive painting, the primer uses a 0.7mm nozzle, the basecoat uses a 0.3mm nozzle, the laquer, uses a 0.5mm nozzle, this is because the 3 different materials have different viscosity so you have to adjust the nozzle size accordingly.

 

I wouldn't drill out a nozzle as they are shaped internally to accept the shape of the fluid needle to prevent drips.

It might be worth asking a specialist bodyshop supplier (such as Brown brothers) if they can get the size nozzle that you're after.

[ayjay]

http://community.ceramicartsdaily.org/forum/19-ceramic-arts-daily-forums/ or some other ceramics forum is probably better for this sort of information.

I agree, you would think so, and I'll ask at CAD later (I'm a member there already), but I already know that the majority of responses will say what works for them and that they just use the cheapest guns from Harbour Freight; (the majority of CAD members are USA based), and they probably have larger compressors than mine which will work with any gun/nozzle.

 

HVLP with a 2.0mm nozzle usually wants anywhere between 7 & 12 CFM - but then it gets more complicated, I won't be spraying continuously, probably a few seconds at a time, does this mean I can use a smaller compressor successfully or not?

 

I would think that the ceramic glaze is a lot thicker than what spray paint is, so you would need a larger nozzle to allow the same amount of fluid through to give a good even coating.

 

 

I wouldn't drill out a nozzle as they are shaped internally to accept the shape of the fluid needle to prevent drips.

It might be worth asking a specialist bodyshop supplier (such as Brown brothers) if they can get the size nozzle that you're after.

 

I don't know how thick spray paint is - I have no experience of spraying other than using the College stuff on ceramics: ceramic glaze is about the consistency of single cream (or top of the milk if you can remember when milk had a creamy top).

 

A few drips wont hurt when a glaze is being sprayed, once it's dried after a few minutes they could be rubbed off with a finger, or left on depending on the glaze, some will flatten out more than others when fired, drips and runs in glaze can also create darker/lighter areas and often enhance the look of something when it's finished.

 

 

 

 

 

 

[poledark]

Why not just brush it on...or use a finger tip........would give an interesting finish?

 

 

Just kidding...good luck with your search

 

Den

[ayjay]

Why not just brush it on...or use a finger tip........would give an interesting finish?

 

 

Just kidding...good luck with your search

 

Den

 

 

Brushing is possible with the addition of gums to the glaze, without gum the water is instantly sucked out of the glaze on the brush and the whole thing can end up very messy.

 

It needs to end up about 2mm thick on the pot so you need at least three brush coats to get the right amount on, it's not practical on a large scale, I'm not ever likely to be making things in those sort of quantities but a sprayed finish is often just so much better looking.

 

Finger swipes are a known device for creating effects in a glazed pot, but not for a complete application.

 

 

.........and some pots don't lend themselves to neat brushing.

 

 

This one was brushed, (it needs a bit more Silica or Boron and a bit less Feldspar in the glaze to cure the crazing).

 

[JV44]

Ajay before we swapped to airless spraying I used a devilbis [spelling[]spray gun for laquer work etc ...long time ago now so cannot remember tip size etc ,not what you want to hear but this may be worth a look all the benefits of airless without cleaning out a big pressure line....spray nearly everything neat without thining

http://www.caneadam.co.uk/p/128/graco-easymax-wp-cordless-airless-sprayer?gclid=CLuUlv26xLsCFTMdtAodu28AZQ

 

Worth a call to see Steve

[Si...]

Spray paint has the same consistency as water, hence why you use a very small nozzle for spraying it, something like the consistency of single cream is very similar to the primer that is used on car paining techniques, so you might be able to get away with a 1.00mm tip

 

 

You should be able to get away with that compressor as long as you let the tank fill up after each use and don't spray for more than 30 sec at a time.

[ayjay]

Spray paint has the same consistency as water, hence why you use a very small nozzle for spraying it, something like the consistency of single cream is very similar to the primer that is used on car paining techniques, so you might be able to get away with a 1.00mm tip

 

 

You should be able to get away with that compressor as long as you let the tank fill up after each use and don't spray for more than 30 sec at a time.

Ah, good stuff, now we're getting somewhere, for the price of a cheap gun I'm prepared to give it a go with a 1.0mm nozzle and see what happens, I can thin the glaze down some more if necessary, but the nearer I can keep it to the ideal consistency the better it is, changing it just means more testing*.

 

Looking back in my mind to when I've sprayed pots before, 30 seconds would be a long time, so that's the sort of thing I was hoping to hear.

 

*Pro potters are endlessly testing, but then they are probably firing a kiln every couple of days, I don't fire often enough (and am not always organised enough) to test things out like I should.

 

Ajay before we swapped to airless spraying I used a devilbis [spelling[]spray gun for laquer work etc ...long time ago now so cannot remember tip size etc ,not what you want to hear but this may be worth a look all the benefits of airless without cleaning out a big pressure line....spray nearly everything neat without thining

http://www.caneadam.co.uk/p/128/graco-easymax-wp-cordless-airless-sprayer?gclid=CLuUlv26xLsCFTMdtAodu28AZQ

 

Worth a call to see Steve

 

Price is a bit rich for me Steve, (it's only a hobby after all's said and done), cleaning is not a problem with ceramic glazes, it's all water based, you can just fill the pot with water and spray it through, even if it's been left for a couple of days, a soak in warm soapy water and it's clean again.

[Newt]

If you have a compressor that fills a tank and you take pressure from the tank, a small compressor should work fine and actually give you more control over the pressure you send to the spray gun.

 

I have a large direct pressure compressor in the shop and a smaller tank style that will put up to 110 pounds of pressure in the tank for doing small jobs away from the shop but both are normally used to operate pneumatic tools so I'm useless for info about using them to spray stuff.

 

Harbor Freight is a great source for low cost tools but you have to know going in that it also means they aren't long-life, high quality tools. We have a Northern Tools which is similar and closer to were I live so I do most of my light-duty tool buying from them.