need some help with waterborne

[martens]

Im a pretty inexperienced sprayer and I'm now switching to waterborne (I work from home and have neighbours).

Im using an MlCampbell precat white paint for my first project.
I sprayed a few samples and they turned out like crap....the paint didn't level...my test pieces literally looked like melamine.

It felt like I wasn't getting enough product out the gun...?

My questions are , what size of tip should I use (very high pigment paint)?

And what kinda air pressure to the gun?

Im using a SATA rp with a 1.3 tip and basically giving the gun 100psi. I read 30-40 psi max but at that pressure I was getting worse results.

really appreciate any feedback... in a bit of a bind here

 

[Wittler1507]

Hi Martins, I'm new at spraying to, and gearing up to do my kitchen so very interested in your question.  Would you mind explaining when you say flat were you expecting a gloss finish?  Melamine is a very smooth finish.

 

[ccmviking]

Im using a SATA rp with a 1.3 tip and basically giving the gun 100psi. I read 30-40 psi max but at that pressure I was getting worse results.

really appreciate any feedback... in a bit of a bind here

1.3 is going to be way too small for waterborne.  While you can also have other issues going on I use a SataJet 4000 RP with a 2.0 set, and it works very well for me. 

Chris...

 

[martens]

Thanks Chris looks like I'll be buying a new gun (should have 2 anyways)

I'll try and attach a picture to show what I mean

 

[BPCFinishing]

Yep definitely a bigger nozzle, with the right size nozzle (probably 2.0) you'll get good flow at 20-30psi at the gun.

 

[martens]

Well I found a Devillbiss GTi with a 1.8 tip for $140 so I'll give that a try.

Thanks.

 

[JCLP]

Well I found a Devillbiss GTi with a 1.8 tip for $140 so I'll give that a try.

Thanks.

Good morning. Spraying waterborne takes a lot of practice. I see from your photo that you are getting what I got when I initially started spraying. Using a 1.3mm needle, stage 3 turbine and thinning the paint by 10% I was able to achieve great results. One thing I learned was that you need to spray the paint thicker. I found with waterborne products, probably others as well, that I needed to spray between 3.4 and 4.0 wet mils as per the TDS sheet of the paint I'm using. If you spray to thin you will get a rough gritty surface.
Cheers,
JC

 

[junk731]

I don't know how much research you've done but the Sata RP is not listed from spraying WB products and the DV GTI depending on the age is an automotive gun and needs a lot of air, 15CFM. That being said if you get the product thinned right to flow you should get reasonable results. I find ML Campbell products to be problematic when it comes to their WB opaque finishes. Recently tried them but was disappointed for the last time. The first coat applied very nice but subsequent were plagued with microbubbles and cratering. I called customer service and he told me I didn't mix it well enough and to use a power mixer. Tried his suggestion and made the problem worse. He then said their was nothing he could do and to go back to the dealer. Went back to the dealer and he said that it was a problem product. Switched to SW and all my problems magically went away. Read some of the threads on the forum and you will get some more help.

John

 

[Klemm]

some good suggestions here. If you're considering SATA again, call Tony Larimer at DanAm the US Importer . Really knows his products and applications. Perhaps wait till after the IWF Show ending 27th.
Hans

 

[martens]

Thanks guys.
The SATA RP is just what I happen to have and the GTi I came across at a pawnshop and picked it up just because it had a bigger tip.

I was told all I can do for thinning is 5% water and max 3% aqua star flow additive?

I really want to like Water Borne, I'll keep trying things out.
Maybe I'll have an excuse to buy a brand new SATA

 

[martens]

Well I got it to lay down pretty flat...new problem is that the primer is causing the MDF door panels to raise leaving a texture look. Might try out the Valspar WB next. This has been a disaster.

 

[martens]

I'm thinning no more than 3%...running 50psi to the gun and then adjusting down from there.
Looks like I'll have to paint everything 2X.

 

[tjbnwi]

Well I got it to lay down pretty flat...new problem is that the primer is causing the MDF door panels to raise leaving a texture look. Might try out the Valspar WB next. This has been a disaster.

What primer you using?

Not sure if ML Campbell has a sealer, if so use that first, sand. My go to is SW KA+ Surfacer, you could also brush on Seal Coat then sand. I do not recommend spraying Seal Coat in the average home shop.

Tom

 

[martens]

Just using the ML stain blocking primer.
So sealer then primer then paint?

 

[tjbnwi]

Just using the ML stain blocking primer.
So sealer then primer then paint?

Yes. MDF can be finicky because there is such a variation in quality. Cut edges can drive one crazy.

Tom

 

[rnt80]

I agree with Tom, the quality of mdf varies widely.  Using waterborne products can present a few challenges and this is one that I've found consistently.  Most of my paint grade jobs use doors with 1/4" mdf panels and even after laying down two coats of sander, both sanded smooth, I'll still get some raising with the mdf.

 

[Michael Kellough]

Is there a water based primer that can be sprayed directly on MDF?

My experience with MDF is that it explodes in contact with water. Ok "explodes" is a gross exaggeration but I'd never consider using anything but an oil based primer on MDF. Even shellac based BIN causes the grain to come up on MDF.

If there is a water based primer that can be sprayed directly on MDF I'd sure like to buy it.

 

[tjbnwi]

Is there a water based primer that can be sprayed directly on MDF?

My experience with MDF is that it explodes in contact with water. Ok "explodes" is a gross exaggeration but I'd never consider using anything but an oil based primer on MDF. Even shellac based BIN causes the grain to come up on MDF.

If there is a water based primer that can be sprayed directly on MDF I'd sure like to buy it.

I've used SW Wall & Wood and the KA + Surfacer, both with great success and issues. Depends on the product.

Tom

 

[Michael Kellough]

Thanks Tom, I'll have to try some. Maybe my MDF is just meh.

 

[martens]

So am I able to just use me usual (acroma) solvent base primer and the water base paint ontop?