Wireless Set No. 52 Canadian - Project

[David Dunlop]

Well here is what a test board looked like after an attempt to spray paint a finish coat on it with my new Preval system.

The paint is an oil based, rust resistant enamel the manufacturer advises not to thin, and to use Mineral Spirits for clean up work. Under that advise, the system could not get the paint out of the spray jar.

Step 2 was to start over with a new system assembly and thin with Mineral Spirits at 4:1, as recommended by the system maker, ensuring the filter assembly at the bottom of the intake tube was removed. Paint barely made it out the nozzle and produced the attached fine textured orange peel look. Not even close to what I need. Tossed that system as well.

Now I am thinking about what to do next. At least the colour is exactly what I wanted.


David

[Jordan Baker]

It’s hard to say from the picture but if it’s a dry dusty sandpaper feel to the paint it’s either too thick still or too much air pressure is being used. This causes the paint particles to dry while airborne. If the paint is too thin you would just have to do light coats and build up the colour. In the model kit world I am for a milk like consistency of paint for spraying.

[David Dunlop]

Hi Jordan.

Thanks for your comments. Much appreciated.

Your observations are on the mark. The paint on both attempts went down in a fine spatter. The Mineral Spirits has a very slow evaporation rate and the test board was still wet after six hours in the house and did not dry to the touch for about 16 hours. When dry, it indeed feels like fine sandpaper.

I was hoping to avoid hauling out my main spray gun setup from the basement out to the garage to work this all out but that is clearly in the cards now. Wind, dust, bugs and a long walk to the house are not my friends and it is shaping up to be a stinky hot weekend here.

My gut tells me the 4:1 mix ratio of paint to thinner is probably correct. The little Preval system could just not deliver the paint. So, I shall start another test, weather permitting next weekend at 4:1, with the compressor at 40 psi, which will provide a proper air volume. If the paint flows well I will move directly to the required finish work. If it still spatters, I will try a remix at 3:1 and see what happens.

Must say I am not fond of working with the mineral spirits, turpentine and varsol family of thinners any more. They take forever to dry and always seem to leave a greasy feeling residue.

Also miss my old spray gun outfit. I had two paint canisters for it and a canister cap so I could have one on standby with thinner for a quick clean of the gun and I could also cap a mixed canister of paint for a while if I needed to do so.

CH seems to have outsourced their parts operation in the USA to several third party dealers and here in Canada I could get a second canister from Grainger, but canister caps no longer appear to be available. Better start raiding Debs stash of jam jar lids to see if one will fit.

I will post again after the weekend, if my sanity allows. Thanks again,


David

[David Dunlop]

Finally. Success!

As of this morning, the front panel of my Coil, Aerial Tuning No. 2 A has a lovely finish coat of the required gloss enamel.

I ended up chatting with our Head Body Shop Painter at work last week and took him my spray gun to have a look at. He confirmed the setup needed for it to operate as a Pressure Fed, Internal Mixed gun and also confirmed the wrong parts package came with the gun. It had one extra piece completely irrelevant for the model of gun and the Allan Key supplied was not the correct size. Raided my spare keys box and got the correct size.

I will post a photo of the panel later today, after I come back down from my current Happy Place.


David

[David Dunlop]

It has been eight hours since I painted the front panel and the paint is still wet. Mind you the panel is sitting on my work table in the basement and the AC has been running in the house most of the afternoon. so I shall give it until Tuesday to see what happens and consider at that time if it needs to come upstairs to dry better.



David

[David Dunlop]

A dawn of a new day and I am right back at square one.

After spending a good hour yesterday morning setting up my spray paint equipment in the garage and getting the paint filtered and mixed to the recommended 4:1 ratio, I took another 20 minutes or so adjusting the spray gun to get, what I thought was a good paint flow...

The test piece I worked on had a nice even gloss to the paint when I switched to the Coil front panel. Again, the paint went down in what appeared to be a nice even glassy gloss. It was a little thicker than I wanted, as a slight ridging was starting to show up around the outside edge of the panel, but I was happy so into the house the panel went to dry. It looked good for about one hour. Then, a mist of what first looked like very tiny bubbles slowly started to appear in the paint. Eight hours in and the paint was still very wet and the misty look even more evident, but at least the perimeter ridging was starting to to disappear.

This morning, 22 hours later, the paint is dry but the finish has turned to sandpaper once again. I have no choice now but to resand this sucker once it hard cures and start over. More time wasted.


David

[Chris Suslowicz]

Not wishing to ruin your day any further, but are you using the correct type of paint? "Varsol" and "Mineral Spirits" are an oil-based (paraffin/turpentine substitute) paint - OK for wood where it can soak in and it's a rough surface anyway, but probably not for metal.

I'd be inclined to try a cellulose-based paint and thinner combination, as used on machinery and vehicles - it's fast-drying and you can use multiple thin coats to build up the thickness if required.

I think the wrinkle/sandpaper effect is due to the slow evaporation of the solvent and consequent small bubble formation as the paint dries.

Best regards,
Chris.
(I have zero painting experience but have watched the production line at Perkins Engines (years ago: mid-1980s) where the completed engine (mounted on a "J Hook") passed in front of a "water wall" to catch the overspray and was spray-painted blue by the operator in under a minute!)