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CNC painting system, another silly idea?

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John Hill:
I have spent some time trying to paint roadsigns on my CNC table.

The first run was OK,  I used regular permanent markers to outline the letters then we 'coloured them in'.

The second run was a disaster because the solvent in the markers softened the base paint that then blocked the marker tips,  tips were munted and the painted base surface spoiled.

So I mounted an airbrush and that looked quite promising until the cheap airbrush showed it's true colours.  It would paint well for about 45 seconds then stopped painting,  it would restart after cycling the needle movement but that also left an unacceptable splodge of paint on the work.  There were hard to stop air leaks and when trying to solve these by tightening the screws the seals ruptured then the threads showed signs of having stripped and the whole airbrush was worth nothing more than a resting place in the skip.  I will not be buying another airbrush until I am certain that would be money well spent.

Meanwhile I am looking for a pen that won't block up,  a spray that will work and not fall to bits or something else that will paint my lettering on the sign boards.

I'm drawing a blank, john, so far about the lettering paint, but am wondering if you could change your base paint to be resistant to the marker solvent.

Markers, I believe, are in the alcohol/acetone solvent class. If base paint is in the oil or polyurethane class then they should not affect each other.

Alcohol/acetone class paints include shellac, lacquer, lacquer type automotive finishes, and Krylon (tm) so I would avoid using those with markers.

Oil based class paints would be the oil enamels, alkyd oil enamels, polyurethanes, and those should not be affected if really dry. Particularly polyurethanes, which have a very high resistance to solvents.

I don't know how markers would affect polymer/acrylic latex water cleanup type paints. Might or might not play well together with markers.

I guess a polyurethane enamel would be my choice. Or you migh consider overcoating any kind of base paint with a clear polyurethane varnish before applying lettering.

John Hill:
Thanks for the paint information.   The base paint on the problem board was a water soluble acrylic with a faint 'chemical' smell,  it took days to dry and I think it was still somewhat soft after a couple of weeks.  The pens were CRC brand paint pens.  I did not try to fill in the lettering with these pens.

I was so disheartened by my airbrush experience and became determined to give them another go so I have ordered another.  I also found advice that simple beeswax can be used to control the air leaks that gave me grief and led to the damage to the first airbrush.  Air brushing has the potential to totally fill the lettering which pens can not really do.

Meanwhile, other members of our museum volunteers have painted more boards for me to do the lettering.  They have used acrylic paint which the tin says is suitable for exterior use, new paint bought for the purpose, unlike the other paint which was really unknown properties and found in our store.

I've seen pens that are airbrush paint reservoirs...  blo-pen, maybe?

Sent from my SM-G715A using Tapatalk

John Hill:
They might be interesting!


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