Advice needed please- Micro bubbles in waterbased finish

[mlarm]

Hi I am after some advice I am at a complete loss as to why I am getting Micro bubbles when spraying teknos joinery coatings.

I have tried different pressures and techniques, I've even sent the pump away to have new packing.
And still it comes back.

Any help would be really appreciated as I am dreading spraying at the moment.

Many Thanks
Matt

 

[RobinBHM]

Some more information would be helpful:

-what size tip are you using? I assume you are using an air assisted airless spray system?

- how are you drying the joinery, is it near a heat source?, high humidity etc do you have fans to circulate air during drying?

- is this in the primer coat or top coat?

-what timber are you using?

I presume you have discussed this with Teknos? -they do have very experienced technical staff.

My experience with micro bubbles is that it is caused by drying too quickly, we found that parts drying nearest to the heater fan were drying with bubbles breaking through the coating. In the summer a similar effect can be caused by sun heating a metal door or tin roof.

I would say start by looking through the parts on your drying rack and seeing if the problem is more noticeable at one section of the parts or one face.

 

[mlarm]

Hi Robin
Thanks for your reply.
I am using a graco 45-1 aaa
tip size 411

Its in both primer and top coat, but worse in top coat.
I am drying with fans after 15 mins flash off, no heat added.
The timber is Accoya

Yes teknos are trying there best however seem a bit miffed as well.

Thanks
Matt

 

[RobinBHM]

Ive not experienced that scenario myself.

We spray accoya with a 30:1 merkur pump and a 4:11 tip and had no problems except with drying too fast causing air bubbles to form. We do sometimes get micro crazing but that we believe was a result to using cold paint back in the winter, havent had that recently.

I assume you've had the pump for a while and it used to be fine? -being as it is in both primer and top sounds more like an application issue than paint, but Im not an expert on whether pumps can cause micro bubbles, so cant advise on that. I do know that Teknos paints are somewhat thixotropic and the pump shear action will break that down although it re-forms on the surface of the paint film.

Have you tried thinning the paint?