Right aileron hinge

The holes for the aileron hinge also stiffens up and shapes the aileron. I almost did a huge mistake here because the ribs, only at the root and tip, pushes the two bent halves a few mm apart. When the aileron is laid upside down and I tried to push with a flat hand at mid span, the surface will come too far down. When released the aileron will have a nice banana shape. What I did was to push the edge down with a file to get the lower surface flat on the table, then hold the hinge in place with my thumb and the other finger at the trailing edge without pushing the surface down. It ended up 100% straight.

Had to try the Topgloss once more as well. This time I rolled on a thicker layer, then use a foam brush to smooth it out. It became better, but far from OK on an airplane. High gloss and brush and roller is not a good combination no matter what the advertising says. Also sprayed some transparent coat on a piece of aluminium that was sanded with 1000 paper. Looks a bit cool, but I'm not convinced.

Aileron

Drilled holes for the ribs in the ailerons. A bit fiddling to make it all fit with all the cutouts.

The whole paint stuff is strange. When I oiled my floor in the new shop I used something called "concrete oil" for indoor use. The name is very misleading because it is no oil at all. It is an acrylic emulsion (latex paint) that soaks the surface and penetrates down into the concrete. When cured it binds the concrete together as well as making a smooth surface and is of course water proof. It is also used as a primer for epoxy floor paints. I am very satisfied with the result, it does exactly what it advertise.

This "latex paint" on airplanes is also an interesting thing, but confusing. I have looked at typical Norwegian house paints and there is no such thing as latex paint. What they call latex paint in the US can be vinyl paint, PVA (Poly Vinyl Acetate) or an acrylic emulsion, all water based. It can also be a mix. In Norway I have only seen PVA and acrylic emulsions. The difference is that the acrylic emulsions are superior to PVA. PVA is typically used on ceilings, and as cheap wall paint. Most acrylic emulsions are indoor paint. There are some acrylic emulsions for outdoor use, but most are alkyd paints, some are also acrylic hybrid water thinned alkyd paints. For vinyl paint I have only seen this primer I am using, but that is alkyd based, not an emulsion, not a "latex paint" in any shape or form.

This Stewart Systems looks interesting. My neighbor meant I could simply put a transparent cote directly on the aluminium sanded with 1000 or something sand paper. That could look very cool, but will it stick?

Aileron

Sanded down the test sheets. I will try to polish them in 14 days and see how that goes, not very optimistic though. Graham Smith at Sprite Aviation could tell me that they use rollers, but only on matt and  satin finish, never on high gloss. Makes sense to me. He also said they mix their own paint because the viscosity is very important and it varies with the actual pigment (color).

Cut the aileron led counter weights with my hand saw. That was several hours of hard labor. I wish I had a band saw.

Topgloss BR

Rubbed down the test sheets and sanded with 400 wet sand paper. I found that the rubbing down was unnecessary because wet sanding with 400 did the trick rather easily. It became really smooth. I thinned the paint with 10% thinner (Jotun number 7), but that did not help one bit, in fact I could see some spots where the thinner dissolved the first coat and the vinyl primer.

The only solution I can see is to apply one more coat (no thinner this time), and then sand with 400 and or 800 and polish the surface. I will apply that coat tomorrow, and try some other brushes as well, a foam brush maybe, and then sand it and leave it for 2 weeks to cure properly, and then polish. If that doesn't work I will dismiss Topgloss BR altogether, also for my boat.

I also tested the paint with acetone and the thinner, Jotun thinner number 7 which is 75% Xylene  and 25% Ethylbezene, and alcohol. All three dissolved the paint very easy. I hope this is because it is not cured yet. The paint is fully dry in 6 h, but is supposed to take at least 5 days to cure at 23 C. The thinner also dissolves the vinyl primer easily, while acetone requires some work. The "Quick" spray enamel paint withstands the thinner, but is affected by acetone a bit better than the vinyl primer. What a mess. In any case it shows that latex paint is not such a bad thing, very strong and flexible. The thing with latex paint though, is it can withstand almost anything except Xylene.

Also received the faulty ribs and spar from Sonex today, so I can start on the vertical tail, once I finish the ailerons.

I had hopes for this Topgloss BR, high tech Polysiloxane that is supposed to be specially made for brush and roller. So far it seems pretty much unusable. I painted my fiber glass canoe some ten years ago with a 2k paint using a brush only, and the finish is 10 times better than this Topgloss BR.

  

Tried the Topgloss BR

Lots of pigment in there and it is glossy, but the finish is nothing to be impressed of. I used the correct roller and finished off with a broad soft brush, as described in the manual. The problem is it is way too viscous to be smooth. Right now it seems back to polishing if not the second coat becomes much better tomorrow evening. Maybe some thinner will help, but to me it seems like it cures too fast.

The only good thing seems to be that it sticks to unprimed aluminium just as good as the primer.

Primers

I have to write this down before I forget. I have tried a whole bunch of primers now. Monopol wash primer, Monopol Strontium chromate epoxy primer, Scanox rattle can (no longer available), Biltema aluminium primer, Duplicolor aluminium primer, Duplicolor plastic primer, some old zinc chromate primer, Jotun Yachting rattle can Vinyl primer and Jotun Yachting canned vinyl primer. I have also tried rattle can top coats.

Biltema and Duplicolor gives a very nice finish and are very easy to use. They look really nice, but when testing physical and chemical strength they are extremely poor. A drop of acetone will destroy large areas.

The Scanox (quick) rattle can is a bit more difficult to use, but it is much stronger physically and chemically than Biltema/Duplicolor.

Monopol wash primer is really good. It is for professional use. But the surface is porous and therefore it must be covered with something. As a primer for outside top coat it is probably as good as it gets. But it really is not something to use inside the house, the VOC content and odor is beyond belief.

The Strontium Chromate Epoxy is the best overall. Extremely strong, yet only 10-20 micrometer thick, and can handle even Acetone in moderately amounts, and is totally corrosion proof. But, it is not for the house due to VOC and toxicity and it is a lot of work.

The old zink chromate rattle can is easy to use, but it is thick and not very strong. It is also practically impossible to get.

The Vinyl primer is a bit difficult to use from the rattle can. But when cured over night it is very strong, and it even handles acetone to some extent, not nearly as much as the epoxy, but remarkably well. It is the only one together with the epoxy that is 100% waterproof. It can also be brushed on, and this is really practical when priming only the mating surfaces. In addition it can be used everywhere, on all substrates, and it is non toxic. And of course, it is part of Jotun Yachting system with the Polysiloxane top coat and is available everywhere around here. I just hope the rolling of the polysiloxane turns out OK.

Ailerons, primer and top coat

Bought Topgloss BR (Polysiloxane) at COOP along with some rollers and other stash. Then I went to the drug store and got some 60 ml syringes so I can accurately mix smaller amounts of the Topgloss. The syringes were surprisingly inexpensive, 3.5 NOK or about 0.4 Euro a piece.

Finished deburring the cutouts in the ailerons and measured up all the rivets for the ribs. Then I scuffed a test sheet of aluminium to test the Topgloss. I primed half of it with the vinyl primer and left the other half, just to find out how the Topgloss is with primer and without primer. I let it dry until tomorrow. The sheet is actually a faulty piece of RV horizontal stab skin. I really miss my old priming booth when testing all these primers and coating.

I haven't heard anything from Jotun about using Topgloss BR with no primer, so I just have to try it and see how it goes. If this works out, I will coat the whole plane with Topgloss instead of polishing. I'm not too keen on coating the whole plane with this vinyl primer with rattle cans though. If a primer is needed, then my old Monopol wash/etch primer gives a really smooth and thin coat, if it is compatible with Topgloss. But it is also possible to thin out the canned version of the vinyl primer and spray it on with air and achieve the same thickness as the wash primer (30-40 micrometers). Theoretically a 35 micrometer primer covered with a 35 micrometer Topgloss BR gives a total added weight of approximately 2 kg. This weight penalty is nothing when knowing that the polysiloxane is better than any polyurethane out there. In the cockpit I can also use Topgloss BR, hopefully with no primer.

Then the whole plane will be "Pegasus Grey" with tips and cowling in "Draco Red" and maybe with some trimmings in Draco Red as well.