More on spray technique

[totoblue]

I am a newbie, spraying doors with acrylic satin trim paint using HVLP Wagner HV660 gun.

I am doing one coat as a very light horizontal pass , then immediately a heavier vertical pass so that the the wet coat reflects fairly well but not so heavily that it runs.

I'm finding it hard to evenly apply the paint due to the size of the door 60cm x 200 cm. The gun paints a fan about 8 cm wide plus overlap, so there are a lot of narrow strips to paint and a lot of scope to get uneven coating. I am using the manual recommended 5-15cm distance from gun to target.

Once you've finished a coat, if you see areas where the paint is not as heavily applied as other spots, is it best to leave that hoping the next coat will cover it or to immediately try to patch it up to make it even (not having much success at the latter)?

Is it best to use one very light pass immediately followed by one heavier pass to get the required amount of paint in a coat? Or should I do build up one coat from several light passes to build up to the required amount of paint in one coat?

I've also tried to position my head so that I can see the reflection of the paint I'm applying at *all* times but that is hard on the neck and back and it doesn't seem to result in better application anyway. It's hard to apply even movements when you are bent over instead of standing normally.

[Kev Y.]

totoblue, Spraying is not as easy as it seems... one of the main problems most people face is that they "roll" their wrist as they move across the area to be painted, this gives a thin patch at the edges and a thicker area in the center.

Try and "lock" your wrist parralell to the work surface.

DONT try and "touch up" what appear to be light patches on thge surface, wait till the paint is dry then recoat the whole surface.

and for what its worth, I am from the old school where we NEVER used acrylic on doors, windows or architraves.. being a generally "soft" finish acrylic takes a long time to dry full thickness and in the past I have seen doors and windows glue together. I tend to use enamel for my doors etc, it dries harder and should be more durable..

hope this is of some use to you

[totoblue]

I believe my problem has been that the paint is drying too fast for the technique I was using.

I was building up a coat by going over the entire door in horizontal passes and then going back and going over the entire door again in vertical passes (as in the Wagner manual). However the paint dried before I got back to the same spot again so the paint didn't build-up wet on wet so the gloss levels were uneven.

I find that if I make many passes across the door in each strip, moving each pass maybe across 2mm, so that the surface ends up wet and shiny, then I am painting wet on wet and so I don't get the drying out problem and the gloss levels are even.

I'll try turning up the paint flow next time to see if that makes it quicker.

I measured the temperature of the air coming out of the turbine the other day and it was 35 degrees out of the turbine and 25 degrees ambient. Perhaps that causes drying out, along with the speed of the air bleeding from the front of the gun.

Wagner have a paint additive/thinner specifically for spraying acrylic in their guns - it's called Wagner Paint Easy. Bunnings don't stock it. Anyone know anywhere in Melbourne's east where I can see the package? Unclear if they intend it for airless or HVLP.
You can get it by mail order here
http://www.airless.com.au/DIY%20Spray%20Systems.htm

[durwood]

I think we need a bit more information!

I can't see the gun you are talking about on the Wagner site.

First guess is you have a gun not suitable to spray lacquer

What exactly is the lacquer you are using?

[durwood]

totoblue,
Sorry i didn't see your first thread you posted.

I assumed when you said acrylic you meant lacquer but I see you are using water based acrylic.

Being water its even more likely your gun or your settings are way off as water dries slow compared to other paints, usually it will run as it takes so long to evaporate compared to solvents.


When you sprayed the 60cm x 200cm panels you should have put a coat on the whole face in about 20-30 seconds ( how long is it taking you to apply a coat?)

Second you need to have a wet coat as you spray, if you are going across a panel (60cm wide )the fan should be still wet at the start of the pass when you get to the end and when you return to the other end it should still be wet as you have to have a continuous wet surface to spray onto or you will get a mark where you spray wet paint onto a dry surface. If this is happening its probably because there is far too little paint coming out of the gun. Turn the control knob behind the needle until you get a wet coat which actually runs and then turn it back till it isn't enough paint to run away.



Only put on one coat at a time,it should be wet and on the verge of running, let it dry out and apply the next one and let it dry. Two coats should be enough, Spray the surface across the narrow measurement as you can go backwards and forwards onto wetter paint than if you go long ways. There is no need to go at right angles for the second coat. If you go long ways you will need to have more paint coming out of the gun and be moving faster to get back to the other end while its still wet.

You should have the gun at least 15 cm with the fan open wide this way the paint coming out of the gun will be about the same as using a 100mm brush. Only over lap onto the previous pass about a third of the fans width this way the paint will run into the previous pass and stop a mark forming .

I would expect to have a surface which was wet all over the panel still after I had finished putting a coat on.

If the paint is still coming out and drying too quick you may have far too much air which will dry out the mix as it leaves the gun.

[totoblue]

Thanks Durwood. Based on your very helpful post which I printed out as a reference while spraying, I have turned up the paint flow nearly to the maximum and painted much faster. The whole door is now still wet after I have finished and it has come out much better.

I previously had the paint flow set near the minimum and was doing light coats as "they" always say to do. It was taking me at least 5 minutes to do one door.

The finish is now better than a brush and it passes the satisfied wife test.

I used Dulux Wash n Wear 101 semi gloss acrylic this time to see if it sprays better than the Dimensions Kitchen and Bathroom satin acrylic but it doesn't seem to be any better (and 1 litre of Dulux cost $31 vs $30-something for 2 litres of Dimensions).

There are a couple of spatters in the Dulux 101 but I think that is caused by the paint not liking to be thinned that much and maybe I need to shake the gun to mix the paint evenly. Interestingly the Dulux diluted with Floetrol and water has been sitting in the jar for 2 days since I sprayed and it has separated (in fact it separates in less than 12 hours). The Dimensions diluted the same way has been sitting in a jar for several days longer and it hasn't separated, so it seems the Dimensions is better for diluting and thus better for spraying.

You can't adjust air pressure on this gun. The only adjustments are for paint flow and the type of spray pattern (round, horizontal or vertical fan).

I misquoted the model number above. It is really a W660
http://www.wagnerspraytech.com.au/po...062,59414.html
This is the 2nd top of the range HVLP gun in the Wagner DIY range.

It is all plastic so definitely not a pro gun as I would imagine it would wear out too fast. Plastic is easy to clean however (a toothpick helps) and won't corrode. Bunnings don't sell parts for it that I could see but presumably you could order parts as Wagner list part numbers for replacement needles, nozzle, nozzle seals etc. You can buy whole guns (everything except the handle) for $39 at Bunnings which includes nozzle etc. There are different guns available: a detail gun, a gun with an extension for spraying inside cupboards etc, a gun for large items like fences and the standard gun. The other thing that might need replacing is the air filter which is washable but a bit hard to clean. I've put a stocking over it to catch most of the crap for next time.

[durwood]

Looks like you have your problems nailed.

The Wagner gun is "just" a gun. not really something I would advise anyone getting but as you have found out it will work OK.

Try to adjust the amount of paint so you are spraying at a comfortable rate. It should take you about 3 seconds to pass over 60cm.You don't want to be moving so fast you can't check how everything is going. If you cut down the paint you can move the gun slower and get the same amount on the surface.

The main idea behind spraying is to do the job faster but unlike brushing or rolling its tempting to go over the first coat a second time as you are not touching the first wet coat like you would be if brushing or rolling. You get a better finish but loose a lot of the paint as overspray.

A lot of people think its Ok to keep loading on paint but you should always look what the manufacturer says.

The paints you are using would normally be brushed or rolled and they will put on about the same amount of paint as spraying so apply a coat and wait the required time to add the next coat. Usually 2 is enough, if you put on a second coat while the first is still drying you stop the first from drying out properly. You can't wait too ;long but you can be too quick applying the second coat. I'de always wait longer than is necessary as water dries pretty slow and is not as good at drying as solvent based paints.

Water based paints used in industry ( such as motor , aircraft etc) need booths with special blowers to help speed up the drying as they are so slow.

Always stir the paint well before and after thinning and strain into the gun ( nylon stocking works well) stir it before spraying and do so again if you leave the paint for a long peroid in the gun. A handy hint is to put a few marbles in the pot and shake it before you start spraying if you find the particular paint settles quickly.