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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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 Posted Friday, January 8, 2010 @ 05:33 PM
The next step with the fuselage fiberglass is to make any repairs, sand, fill, remove the amine blush (the shinny surface of the fiberglass)... it comes off with some ammonia/water and 3M stripping pad.. and/or sanding. I want to be careful not to sand through the fiberglass cloth so I use 120 grit. But with the fuselage surface being uneven where the plywood goes over the ribs, I am not trying for a completely plastic looking aircraft as it would require too much fill material. A long sanding block sands the high points and cuts through the thin fiberglass coating so I am trying to be real careful. Even though the aircraft is not going to be in water, I do want it to hold up well without water/moisture damage. Steve was the West coast distributor for West Systems before they went retail, so he knows his stuff.... and "polyester resin" is bad news around water as it attracts moisture. They are very careful with all the materials to make sure they work together. After considerable research I decided to use an MEK based Duratec Vinyl Ester Primer over the fiberglass. It is the same primer used by Steve on his boats... he told me come over, bring new paint cans and pick up two gallons. Once this Vinyl Ester Primer is on and sanded, it will be ready for a thin primer before the final covering of paint. Here are some more images and you can see where I get my materials. I am not sure some of these products are even available for the retail market.
http://picasaweb.google.com/lh/sredir?uname=Bomar1&target=PHOTO&id=5424459989584524690&aid=5424046583236888817&authkey=Gv1sRgCKrDrpqbyvH6wQE&feat=email
More later when the primer is complete...
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eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
Status: Offline
Posts: 294
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Posted Saturday, January 9, 2010 @ 02:44 PM
Just one more suggestion. Do not use dark colours on epoxy, it doesn'n like it. This is why gliders are white. At last it's not a problem of resistence / hardness, but there is the possibility that some small bubbles will sort out.
No problem about UV, all new generation paints and primer are anti-UV.
Try also to plasticize the primer and use it on a sample of fabric covered structure, that way if it works, you can use the same product all over the aircraft. I use 2K sealer primer plasticized, but I think the one your buddy suggested is OK the same.
Eugenio
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Monday, January 11, 2010 @ 12:30 PM
Eugenio: Your suggestion that I do a test using the primer on fabric is greatly appreciated... I will set up a number of fabric samples and see what happens. I have been reading the application sheets on 2K sealer primer... when you say "plasticized" what do you mean?? It appears that 2k primer is made by a number of companies, e.g., Kirker, Ditzler,DuPont, Lessonal, etc. What product to you use and do you add anything to make it more plastic?
Now that autos have so many plastic parts like trim and bumpers, all these paint companies have had to make paint and primers work on both the metal and plastic... which is a good thing for us.
Anyway, please let me know specifically what products you use.... I am most concerned with the paint over the fabric wing sections (which covers both the fiberglass sections over wood and the fabric sections between the ribs). Do you build up with something like Poly bush and Poly Spray.. then use a primer over the silver UV coat?? So please start with the material you use to adhere the fabric to the fiberglass (Poly Tack??), then after heat shrinking (or do you use another process), material to encapsulate the fabric (like Poly Brush), then the primer over the fiberglass and fabric together (the wings)...
Regards,
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eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
Status: Offline
Posts: 294
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Posted Monday, January 11, 2010 @ 03:52 PM
All 2k primers are more or less the same stuff, you only pay the brand name. I use industrial primers and coatings and I'm satisfied with the result. You don't need a mirror surface on wood and fabric, because this will only magnify every little defect and is not "like the original"
Up to now I used DU Pont plasticizer, that is really effective but expensive. I have been told that can be used also banana oil or castor oil, but I had not the time to make samples, so I cannot say it's ok or not.
In any case the percentage needed is between 5 to 10%, not much more or your primer or paint will remain tacky and feel like gum.
Absolutely do not use silver UV coats, it is useless and is difficult to paint over. The primer iself (but also all enamels) already are UV protective.
I use the dacron fabric produced by Diatex, and following theyr (certified) process, you only need some coats of diluited cement then directly primer and enamel. This is what I succesfully do in our jobs. Obviously this will horrify those used to cover all with fabric with the old and proven system with butyrate, UV coats etc. but I can assure it works.
Eugenio
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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
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Posted Monday, January 25, 2010 @ 04:14 PM
Bob,
How goes the sanding and filling of your fuselage? I had real concerns about sanding through the fiberglass in trying to fill and smooth it out, so I've halted my rebuilding for the moment to see how you're doing it. It looks like your fiberglass went down very smoothly. Maybe you don't need a lot of sanding.
--------------------
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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Bob Brock
Master Sergeant
Gender: Male
Location: Portland, Oregon
Registered: Mar 2009
Status: Offline
Posts: 156
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Posted Monday, January 25, 2010 @ 11:21 PM
Greetings:
Great timing... I was just going to give a progress report. As I go over the fuselage there are a number of areas that need attention. One of the nice things about going down to the wood and having everything apart, is that you can see water stains and where some fittings have rusted, etc.... so I am trying to fix these little things as I go. I put together 7 pictures to show you some of the items, but others include holes made by the wood screws that I have filled with epoxy material. I don't know if it will help any, but I reinforced the tail wheel attachment point with about 4 layers of 6 oz fiberglass cloth. I wanted to make this really water proof and stronger. Also I want to keep water out of the fuselage in areas like the tail lift handles. Actually I was going to remove them completely but they are really attached inside the bulkhead and not easy to remove.
http://picasaweb.google.com/lh/sredir?uname=Bomar1&target=PHOTO&id=5430878878834926514&aid=5430878862788408641&authkey=Gv1sRgCIKE3LnX2oDB6gE&feat=email
Most of the fuselage does not need much sanding or use of the 3M pad... it is mainly the seams and where the fabric overlapped.. but it really sands off nicely, just have to be careful not to take off too much. More later...
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