Spraying technique

[totoblue]

I've just bought a Wagner W 660 HVLP spray unit and now I'm learning how to use it.

My first use is to spray old wardrobe doors. Obviously I'm not after a perfect finish for old doors - I just want to avoid brush and roller marks.

I am spraying satin finish acrylic paint (can says it is ok for spray) - Dimensions brand (which is Dulux). To get it thin enough for the cup test included with the gun I have to add about 40% water. I also added 15% Floetrol prior to the water - however while Floetrol says it makes spraying easier, it also says it doesn't thin the paint and I proved that by doing the cup viscosity check. I should have started with the spray gun on top of the undercoat which I'd got real smooth with sanding, but I'd already done two coats of topcoat with a good brush before I succumbed and bought the spray unit.

I have 3 questions so far.

1. How much paint should I be applying in each coat? I have been doing light coats (first a very light coat in horizontal bands then a slightly heavier coat over the top straight away in vertical bands - as advised in the manual). It's coming out matt (not satin) and I'm not sure if that's because of the watering down of the paint (Floetrol label says it doesn't alter gloss levels but implies that watering down will do it) or if it is because I haven't put on enough paint in each coat (where I've applied heavier coats it's more toward satin than matt) or if it is too few coats so far.

2. How the *^%% do you see what you're doing? I am spraying white paint on white and it is extremely difficult to see how much paint is being applied to each spot. I am spraying right next to a large south-facing window and I have to have a 500w floodlight on the door to see what I am doing and then I have to position the light and my head so I can see the reflection of the wet paint. What sort of lights are best? I have some concern that the 500w flood is prematurely drying the paint although it does seem to stay wet after it reaches the door. Or are the experts just able to spray without seeing exactly what they are doing?

3. Should I use a round spray pattern or a fan pattern? I'm using round at the moment.

Can anyone point me to outstanding threads on spraying on this forum or other links to spray technique? At the moment, I'm looking for spraying acrylic paint on trim, doors, furniture and eventually spraying MDF kitchen doors (perhaps with ordinary paint or with specialist e.g. Mirotone).

I've waded through some of the search results but most of the hits are newbies like me asking questions and not a lot of meat.

One good thread I've found so far is...

Spraying Kitchen finishes
http://www.woodworkforums.ubeaut.com.au/showthread.php?p=256162

[keepontruckin]

I have a wagner spray beaver and it sprays acrylic paints without thinning. As a painter and decorator by trade, paint what you are painting in good light. Start from the light and work away. That way you can see what you have hit and missed. Another tip is to move the gun quickly and evenly. Two coats will cover easily.

[Jstegall]

Here is a link to a manual that seems to be well written. See if it helps (it is a US site)
http://www.targetcoatings.com/manual.html

They also link some work by Jeff Jewitt who seems to know his stuff also.
John

[Kev Y.]

1.[snip] It's coming out matt (not satin)

2. How the *^%% do you see what you're doing?

3. Should I use a round spray pattern or a fan pattern?

http://www.woodworkforums.ubeaut.com.au/showthread.php?p=256162


For my 2 cents worth, If the paint is comming out with a flat finish, it will most probably be due to the acrylic drying before it reached the surface to be painted. to over come this either move the gun closer to the door, or decrease the air flow (if possable)

To see where you have been or are going, watch for the wet edge developed by the fresh paint.

From personal preference I would be using the FAN pattern, with the round pattern you could run the risk of flooding an area and developing a run in the finish.

[totoblue]

Thanks for the replies and the link. I'll check it out.

What I've found is:

I was not applying enough paint. It should be wet and look *almost* like glass after spraying. It is now coming out satin.

Yes I've found a fan pattern better than a round pattern as it is easier to get an even coat.

To see what I'm doing, I am now positioning the item to be sprayed vertically so that I stand with the window on my right (I'm right handed) so I can easily see the reflection of the wet paint. Or if spraying with the item flat, put item between you and window.

Working out how you are going to position the items to be sprayed is important and worth spending some time on. It's quite a bit of thinking when you have 4 doors 600x2000 to paint in a room that's 4x5m.

One US link I saw suggested that paint manufacturers often sell the same paint thickened as a retail paint and without the thickeners as a professional paint. The latter would be better for spraying as it would need less thinning. I'll ask at the paint store next time I'm there.

Oh, yes and wear your respirator. (I've got a Triton powered respirator)

Some good links I've found:

This site is good - there's a few other pages there worth reading too.
It talks about (destructively) measuring the sprayed finish thickness using a wet mil gauge. I'm not sure about the validity of manufacturer specs for wet mil thickness after you've thinned the paint significantly though.
http://www.furniturefinishwizard.com/viscosityandwetmils.htm

Fixing spray paint runs without sanding it all off
http://www.furniturefinishwizard.com/runsag.htm

Orange peel in HVLP water borne finish
http://www.highlandwoodworking.com/index.asp?PageAction=Custom&ID=73

A Beginner's Guide to Spray Finishing
http://www.highlandwoodworking.com/index.asp?PageAction=Custom&ID=79

Dulux paint selector
http://www.duspec.com.au/duspec/LoginControlServlet
(link is top left of this page)
Resene paint selector
http://ezyspec.resene.co.nz/EzySpec/index2.html

The following are about airless spray guns but the paint thickness in the first link and the info about worn tips in the 2nd link are relevant to all guns I think:
http://www.resene.co.nz/paintdec/airless_spray_info.htm
http://www.resene.co.nz/pdf/Spray_Units_Brochure.pdf

BTW the paint I'm using "Dimensions" is a house brand of 3D paint stores - it is made by Dulux but isn't a Dulux brand. One of the best things about it is that it comes in 2 litre cans as well 1 and 4, and it's a bit cheaper than Dulux.