On going anomaly...?

[The Z'eer]

A few weeks back I had a go at spray painting, my first attempt https://www.mig-welding.co.uk/forum/threads/practicing-spray-painting.116588/page-6 the fluid tip on the gun was wide open and due to the heavy finish I've adjusted it and reduced it. Now seeing a flatter overall finish...

However I was still getting tiny raised imperfections and was paranoid that it could be dust in the workshop. I decided (weather dependent) that perhaps spraying outdoors would eliminate this, unfortunately it hasn't but is it dust?

So I contacted John Davey who supplied the Lechler 29107 and I was advised to use thinners upon describing the issue, they felt the paint wasn't atomising properly. I hadn't used any thinners with the previous attempts. So the next attempt thinners were used, 50 ml to 150 paint/hardener. The paint does flow far better and as such I wound the fluid tip back a tad. The finish is better but still these imperfections as present...

I appreciate there's a fair amount of 120 grit scratches but I am simply practicing at present.

My gun is a DeVilbiss GPG with a 1.8 tip, air is filtered via moisture trap and three stage filter, 29 psi as according to data sheet, panel wipe used in the prep stage Paint thoroughly mixed and strained before painting.

I'm struggling to determine the issue here. I appreciate it's a game of trouble shooting, perhaps someone can suggest what may remedy the problem? Thanks

 

[brightspark]

do you sieve the paint once mixed before you tip it in the pot . use your lasses tights . then you can rule out lumps in the paint

 

[steveo3002]

yes looks like dust /dirt

id expect you may always get some

 

[Slowcoach]

Looks like dirt to me.
How much prep are you doing to clean and prep panel prior to putting paint on.
Is it a base coat? Looks a bit flat.

 

[AVI_8]

Difficult to tell from the pictures but it does look like dirt in the paint as opposed to something which has landed on it afterwards, what kind of paint is it 1.8 is quite a large fluid tip, typically for primer

 

[carbon]

I assume this is tinted expoxy primer as you only mention Lechler 29107.
Ive not used Lechler 29107 yet, but to me it looks shiny in the pictures, primer doesnt usually look shiny when cured.

Did the panel have that much orange peel before you started?

Did you follow the ppg spray gun setup that I posted in the other thread and have you got a viscosity cup to check the mixed paint before spraying?

 

[the snooper]

I note from your early posts you say the fluid tip was wide open but you've closed it a little, close it fully then open it until you get a nice even texture free coat, close your fan a little aswell until you get that right as you don’t want to create more paint mist then necessary as this will pull dust down from above and around you causing your problem

 

[The Z'eer]

Looks like dirt to me.
How much prep are you doing to clean and prep panel prior to putting paint on.
Is it a base coat? Looks a bit flat.

Epoxy primer. Panel wiped thoroughly with a cloth to take off the excess.

 

[The Z'eer]

yes looks like dust /dirt

id expect you may always get some

I just don't understand where it's coming from. I never had this issue when using aerosols inside or outside. Surely it can't be the inevitable can it?

 

[jsf55]

How do you clean your gun out after spraying ?

 

[The Z'eer]

Difficult to tell from the pictures but it does look like dirt in the paint as opposed to something which has landed on it afterwards, what kind of paint is it 1.8 is quite a large fluid tip, typically for primer

I wondered if it was something in the paint as well. Data sheet says 1.4-1.8 for the fluid tip.

 

[The Z'eer]

How do you clean your gun out after spraying ?

With gunwash and a cleaning kit, I flush the gunwash through under pressure and clean everything. However this is began when the gun was first used. I've only used it five times for practice

 

[jsf55]

1.8 tip should be fine, cleaning sounds good, i would try filtering the paint next time and examine the bottom of the filter too see if there's any debris in there ?

 

[The Z'eer]

I assume this is tinted expoxy primer as you only mention Lechler 29107.
Ive not used Lechler 29107 yet, but to me it looks shiny in the pictures, primer doesnt usually look shiny when cured.

Did the panel have that much orange peel before you started?

Did you follow the ppg spray gun setup that I posted in the other thread and have you got a viscosity cup to check the mixed paint before spraying?

Yeah it's tinted RAL 841 on the tin. I did take a look at the PPG video, thanks it was of some help but it didn't actually specify what the optimum setting actually was for my GPG, it simply states what was best for the "operator"

The panel was flatted back before painting, no orange peel present. I think the shinyness was more down to my camera than what it looked like in the flesh.

I don't have a viscosity cup, that I will purchase though since from what I just learnt it determines whether paint requires thinning or not.

 

[The Z'eer]

1.8 tip should be fine, cleaning sounds good, i would try filtering the paint next time and examine the bottom of the filter too see if there's any debris in there ?

I strain the paint each time, I did take a look at the guns internal filter and it appeared fine. It's really bugging me

 

[The Z'eer]

I note from your early posts you say the fluid tip was wide open but you've closed it a little, close it fully then open it until you get a nice even texture free coat, close your fan a little aswell until you get that right as you don’t want to create more paint mist then necessary as this will pull dust down from above and around you causing your problem

Thanks for the recommendations I'll endeavour to try those suggestions tomorrow

 

[steveo3002]

much higher pressure /volumes of air vs an aerosol

are you wearing a new paper suit? opening the door between coats ? wet floor ?

 

[carbon]

but it didn't actually specify what the optimum setting actually was for my GPG, it simply states what was best for the "operator"

There are no "these setting work with your spraygun" as a beginer following the procedure of setting the spraygun up helps. When spraying onto paper its easy to see when you get to the point where opening the fluid control causes the paint to run rather than produce a nice even spray pattern. A lot will depend on the viscosity of the paint and the air pressure you use, adjust one thing i.e the paint to thick and it will make a big differnce to how the spraygun is set up.

Get a viscosity cup and thin the primer to get the viscosity to what the paint manufacturer recomends. They include it on the data sheet for a reason, be careful though, make sure what system the paint manufacturer uses. Some will specify din 4 whilst it looks like lechler for the primer dont. A lot of viscosity cups are ford 4 and need different timing to achieve the desired viscosity. See attached pdf for conversion between different systems.

 

[MetalMonkey]

Looks like dust to me.

Even with the best set up you will always get some, but you can cut and buff it out easily.
Obviously not on that panel until you sort the sand scratches, of course.

 

[frank horton]

are u using a water trap/filter......just sometimes the airline is dirty inside.....
I always kept a new one just for spraying....plus 2 water traps for saftey....
Have picked at the lumps...? is it solid or hollow....solid is dirt of some sort, hollow is usually water droplet.....