Finished the right wing spars and ribs, riveted and bolted together ready for fitting of the skin.
Tried to spray on the Jotun Topgloss BR (Polysiloxane) with a new and much better spray gun. The result was very bad. If it is me who is terrible at spraying, or that the paint is not formulated for spraying, I don't know, probably both. It was full of pin holes or fish eyes (I really don't know the difference), looked awful even where no pinholes were seen. But I rubbed the half of the test piece with Biltema rubbing again, and it was all shiny again. Have to get some Biltema Hard Wax tomorrow and see if also that makes it all milky like the two other waxes I tried.
The 3 in 1 paint is very good. It dries in 10-15 minutes, but then it is rather soft. After 3-4 days it gets all hard and nice. J. S. Cock also has a special primer for aluminium. It is the same stuff as this 3 in one, but specially formulated to stick on very smooth surfaces, aluminium and stainless steel in particular but also glass. It is only on larger cans, not rattle cans.
I have this booklet "How to paint your own airplane" by EAA. What a total waste of paper! All it say is Acid etch, Alodine, epoxy primer and polyurethane top coat. Yes, it works and the result will be top, but the problem is that: 1- Acid etch will creep into joints and corrode your airplane from the inside. 2- disposing used Alodine is almost impossible due to hexavalent chrome. 3- Urethane is poisonous and requires a booth and a breather. 4- Epoxy primer isn't even necessary. Doing all this with all these extremely nasty chemicals is not something to do in your home. A heated garage will work, but the main point is that the only corrosion that will exist on a painted surface of aluminium is filiform corrosion, and to prevent it does not require all these stages. The corrosion that causes most problems is galvanic corrosion, and none of this will do anything to prevent it. Besides, these products are impossible to obtain locally, for me at least.
If I should go for Polyurethane, the process will be scuffing with scotchbrite, etch primer or epoxy primer, topcoat. That will last for ages without any filiform corrosion and the finish will be top. If that was to corrode, it would be due to galvanic corrosion caused by fasteners and similar. This will also require a booth, but it is somewhat doable because I can get the stuff locally. But, the equipment (booth, spray guns, breathers etc) seems like a whole lot of money and time for a one time process, that may turn out bad. Sending the airplane to some professionals may very well be a better solution.
What I (still) hope to do is use this Polysiloxane with paint and roller. Then wet sand with 1000+ grit, Biltema rubbing and wax it. It is only this waxing part that is a problem right now, maybe I can do without waxing? For primer I have four choices; Epoxy, etch primer, Vinyl (Jotun) or Polyester (JSC). Epoxy and Vinyl I know will work, etch primer and polyester I have to try first. All this I can do at home, and the end result will be like polyurethane, in some aspects even better (UV). In the cockpit I will use 3 in 1 rattle cans with a top coat of clear satin enamel, or maybe 3 in 1 spray gun with the special reducer that gives a harder satin finish instead of the matte finish.
The other choice is polish.
Tried to spray on the Jotun Topgloss BR (Polysiloxane) with a new and much better spray gun. The result was very bad. If it is me who is terrible at spraying, or that the paint is not formulated for spraying, I don't know, probably both. It was full of pin holes or fish eyes (I really don't know the difference), looked awful even where no pinholes were seen. But I rubbed the half of the test piece with Biltema rubbing again, and it was all shiny again. Have to get some Biltema Hard Wax tomorrow and see if also that makes it all milky like the two other waxes I tried.
The 3 in 1 paint is very good. It dries in 10-15 minutes, but then it is rather soft. After 3-4 days it gets all hard and nice. J. S. Cock also has a special primer for aluminium. It is the same stuff as this 3 in one, but specially formulated to stick on very smooth surfaces, aluminium and stainless steel in particular but also glass. It is only on larger cans, not rattle cans.
I have this booklet "How to paint your own airplane" by EAA. What a total waste of paper! All it say is Acid etch, Alodine, epoxy primer and polyurethane top coat. Yes, it works and the result will be top, but the problem is that: 1- Acid etch will creep into joints and corrode your airplane from the inside. 2- disposing used Alodine is almost impossible due to hexavalent chrome. 3- Urethane is poisonous and requires a booth and a breather. 4- Epoxy primer isn't even necessary. Doing all this with all these extremely nasty chemicals is not something to do in your home. A heated garage will work, but the main point is that the only corrosion that will exist on a painted surface of aluminium is filiform corrosion, and to prevent it does not require all these stages. The corrosion that causes most problems is galvanic corrosion, and none of this will do anything to prevent it. Besides, these products are impossible to obtain locally, for me at least.
If I should go for Polyurethane, the process will be scuffing with scotchbrite, etch primer or epoxy primer, topcoat. That will last for ages without any filiform corrosion and the finish will be top. If that was to corrode, it would be due to galvanic corrosion caused by fasteners and similar. This will also require a booth, but it is somewhat doable because I can get the stuff locally. But, the equipment (booth, spray guns, breathers etc) seems like a whole lot of money and time for a one time process, that may turn out bad. Sending the airplane to some professionals may very well be a better solution.
What I (still) hope to do is use this Polysiloxane with paint and roller. Then wet sand with 1000+ grit, Biltema rubbing and wax it. It is only this waxing part that is a problem right now, maybe I can do without waxing? For primer I have four choices; Epoxy, etch primer, Vinyl (Jotun) or Polyester (JSC). Epoxy and Vinyl I know will work, etch primer and polyester I have to try first. All this I can do at home, and the end result will be like polyurethane, in some aspects even better (UV). In the cockpit I will use 3 in 1 rattle cans with a top coat of clear satin enamel, or maybe 3 in 1 spray gun with the special reducer that gives a harder satin finish instead of the matte finish.
The other choice is polish.
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