Airless Spray Finish Issues

[Neocleous]

Hi everyone,

I’m having issues getting a flat spray finish and I don’t know what the root cause is.

I’m using a Graco Ultra airless sprayer with a 310 tip.
Morels water based primer and paint
I’m spraying at room temperature 21C and about 55% humidity. Drying conditions are the same.
All parts have been sanded to 320 grit between coats and wiped down

When I spray some parts of the piece seem to dry super quick and leave a terrible finish when they dry.

Before I sand them and re spray again I’d really like to know what I’m doing wrong

 

[Rich C]

Are you definitely getting enough paint on those parts, they look a bit thin (though that might just be because they flashed dry)? Maybe try a little water in the paint to avoid it drying too fast?

I've had good results with my graco ultra, but I pretty much only spray tikkurila paints so I've no experience of the morels.

 

[__jvc26]

It looks a bit like incomplete coverage —differential thickness of paint coating leading to different drying time and opportunity for levelling.

Are all parts getting the same coverage/overlap?

 

[Neocleous]

I think so, I’m always concerned about putting too heavy a coat down as the Graco pushes out a lot of material.
could it be some contamination of the parts? Would wiping it down with some IPA help after sanding?

im going to sand them back because they have a leathery texture which isn’t acceptable.

 

[Rich C]

I normally sand and then wipe down with a tack cloth and call it good. I can't see that IPA would have a negative effect though.

Agreed on the texture, that's not ideal.

 

[Neocleous]

I’ll give it another go later this evening and concentrate on my technique.

 

[Gordon Tarling]

What material is that part made of? Looks to me like the water based primer may have affected it somehow.

G.

 

[Neocleous]

Medite MR MDF, the primer is also Morels and went down well

 

[dephill]

Medite MR MDF, the primer is also Morels and went down well

How did it go in the end? Did you figure out the problem?
I’m planning on buying a graco airless for this type of job so just wondering…?