Dipping toe into painting

[DiyNutJob]

Has a spray window from 8 to 10, picking 9. Check list ready to go for the crucial final coat. I want no more mistakes, and am getting rather bored with the panel.

SUPPLIES AND MATERIALS
======================
Respirator, clean
Gloves
Paint
Strainer
Thinner
Waste thinner
Tin openner
Mixing cup
Stirrer
Pipettes/scoop
Paper towels
Airtight rubbish bag
Stand, wrap, and tape
600 grit sandpaper
Nozzle socket and wrench


BEFORE SPRAY
============
Tighten gun nozzle
Flush gun and line
Set gun controls
Set compressor pressure
Check needle sealed
Dust off panel with brush or spare gun
Strain paint
Test spray


BETWEEN COATS
=============
Seal gun tank vent
Stopwatch
Sand out debris, brush/wipe off dust, dry
Unseal gun tank vent


AFTER SPRAY
===========
Dispose paint
Seal tank vent
Fill tank with cleaner
Check needle leak

 

[Mottie]

You forgot just one thing. An anemometer.

 

[DiyNutJob]

You forgot just one thing. An anemometer.

I have them already of different sizes. The degree of flex/sway on the outer branches gives a reliable indication of the local air current.

 

[Mottie]

I have them already of different sizes. The degree of flex/sway on the outer branches gives a reliable indication of the local air current.

Old school. I like it.

 

[DiyNutJob]

I ended up with a peely finish today. 2 turns from closed at 1.5 bar didn't work, giving a dull and dry look. I tested by going over with more passes. That made no difference. 2.5 turns from closed was better. Testing has to continue before the right setting can be discovered. Previous accidental 2 bar full open did work but most of the paint was blown into the air. This made the setting not practical.

Other than the peel, there is no serious dirt issues that can't be sorted out with 1000 grit sanding. So, the panel will be finished after curing. The peel will be improved by hand polishing using cutting compound.

The colour match isn't perfect but passable. I will now commit to a full tin of paint for painting the actual panel I wanted to sort out.

 

[DiyNutJob]

The next panel is the side skirt. It is estimated at less than 320mm x 2000mm = 0.64m^2. This is around 6.25 times the size of the current panel. It looks very do-able for the compressor. The primer and base coat should be easy-piecey. This is a serious panel, and I will be using the R500 exclusively. The panel has been taken off the car to make the job easier.

 

[DiyNutJob]

Training panel complete and going on the car. It's peely left and right (relative to the image), less peely middle and bottom. The debris on the final coat was sanded out and polished, leaving no marks. Wet sanding was possible for the whole panel and could produce significantly better result. I will leave that for the next panel if there is a need. This is the first time I looked into wet sanding and it is easier than I thought. With enough meat on the tough 2k clear coat, risk of doing damage from sanding is low. I am now biased towards higher paint flow when clear coating, with exception of the first coat. A thinner first coat reduces the difficult in dealing with debris that might be in contact with the base coat.

A dirt spot that was repaired by breaking all the way down to the base coat, without touching the base coat, was invisible in the final result.

A dirt spot that was repaired by breaking all the way down to the base coat, with the base coat roughed up slightly, was visible in the final result.

 

[DiyNutJob]

Priming for the 4th panel was completed using R500, 1.3tip, 1.5bar, 3flow, 150ml. The result was pro quality. I estimated the paint requirement at 90ml, but gave it 150ml to allow for transfer loss from containers, strainers, etc. In the end, 150 was a little more than the actual requirement, but not by too much. The same volume should be plenty for the base and clear coats.

There were no serious dirt and dust issues today. I had a large-ish piece of wood splinter going on the wet primer that I quickly picked off with a blade. A blade has to be added to the checklist of material requirements. The checklist was very effective in speeding up the process and preventing errors.

I will be filling imperfections in the panel by hand brushing additional primer and sanding flat. Hand brushing will enable a thicker fill. I will be sanding smooth the primer on the normally visible face of the panel using 600 grit. The panel was prepared using 400 grit before priming. A common suggestion was 320-400 grit.

Not having a gun stand was a significant annoyance. But, an improvisation using the corner of a box was found and acceptable. I could use a smaller cardboard box.

The compressor performed admirably, not a single moment of lost pressure. I counted to 10 between full length passes. 10 would be needed for 2 bars, less for 1.5 bars. Remembering a single number is the easiest.

 

[DiyNutJob]

The primer was easy as I thought. Since I had no major fixes/fills to do, brushing on primer for minor fixes was OK, following by sanding flat. A second coat of primer was made after fixes. The optimal flow rate was found to be at 3.5 turns from closed. While laying down the primer, a ripple effect could be seen on it, indicating an apparent too much material. That was only temporary, it then flattened out while drying. This gave a smoother finish. Appearance of temporary ripples was indication of good flow setting. This speculation was applied for the base coat and it was effective.

Laying down the base coat was easy enough. But it was plagued by white specks of pollen. Unlike the primer, the final coat of the base could not be sanded or manipulated to remove debris without making a mess. This made it significantly more difficult than I hoped. This resulted in applying more and more layers of paint. New layers then attract more pollen. It's a bugger. I attempted spot repair using a 0.3mm tip air brush. It gave a much finer paint texture that reflected the light differently. That was a no go.

The optimal gun setting for the base was: R500, 1.3tip, 1.5bar, 2flow.

 

[DiyNutJob]

The base coat was finished close to perfection. Spot repairs using the normal spraying gun settings was effective in blending in the new paint. Total paint used for the panel was about 250ml. The most effective way I found to remove debris on a coat was rubbing it out through a dragging motion using 600 grit under the thumb. This produced a small repair area. Wetting by washing up liquid and water helped it along.

It's becoming obvious 1k paints are quite good for DIY when the spraying conditions are not ideal. 1k paint dries fast and allows quick repairs within the same spraying session. But 1k paint hasn't the durability. I had 1k clear on the panel previously. I thought the clear had delaminated. It turned out patches of clear were completely gone. What remained, stuck on fine, and I struggled to sand them off. The base coat was also fine.

My next step is to do 2k clear. It's going to be a very slow process because debris fixes can't made until after a day worth of curing.

In terms of my painting skills, priming and base coating are in the bag, despite the challenging spraying environment.

I have one more buy to do with painting, a de-nibbing tool. This will remove debris on hardened paint. Probably won't work on softer new paint.