| Author |
Message |
Jim Huskins (Lostranger)
Registered Member
Username: Lostranger
Post Number: 1
Registered: 8-2007
Posted From: 70.109.4.77
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 11, 2007 - 11:45 am: | |
Five years into the project, I'm finally to the point of painting my 87 Flxible Metro conversion. I reskinned the window area and the former front door cavity with 18 ga. cold rolled steel, and of course the end caps are fiberglass. I don't have any problem with painting those.
The extruded aluminum original skin, however, is another matter. I have it all stripped to bare metal with an 80 grit flap wheel on a side grinder. I have a few corrosion pin holes on both sides of the engine bay which I plan to fill with a bondo type filler. All the aluminum will need to be be smoothed with some sort of surfacer to fill the sanding scratches.
I need some advice on preping/leveling/filling the aluminum before painting. I hear horror stories of painting peeling from aluminum in a few months, and I don't want that happening.
I'm also thinking of filling the joints between the extruded panels for a smooth skin effect. Any advice on this plan would also be appreciated.
TIA |
Ed Jewett (Kristinsgrandpa)
Registered Member
Username: Kristinsgrandpa
Post Number: 337
Registered: 2-2003
Posted From: 64.24.212.108
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 11, 2007 - 3:19 pm: | |
You might check into an aluminum etch.
I've used it before with good success.
Several companies sell it.
Here is a link to Martin Senour. Maybe they will have some info since their Product Data Sheets give a lot of info.
http://www.martinsenour-autopaint.com/pds/martin/mspds.pdf
The aluminum etch I used came from POR 15.
The information I got with the etch was that aluminum starts to corrode within minutes after being sanded/polished. The etch removes the corrosion but you need to paint shortly after rinsing it off. It is an acid so protect youself if you use it. (hands and lungs)
Ed |
marvin pack (Gomer)
Registered Member
Username: Gomer
Post Number: 72
Registered: 3-2007
Posted From: 76.4.136.26
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 11, 2007 - 6:04 pm: | |
hey loststranger; I had to remove the skin on my 4905-gmc I have 090 aluminum and cut to fit and test fit each panel, then I sanded the edges,marked the rivets and drilled the holes and sanded them again. I cleaned with lacquer thinner/lacquer wash and put a self-etching primer on the edges. the reason was to make sure primer was under the rivets and would hold paint around them. After installing the skin I sanded with 120 grit and washed it down again and primed it. later 3-4 months I scuffed the primer real good and made sure that it was still covered without aluminum showing thru and washed it down again with lacquer thinner and put the final coats on the stuff. I had to do it in sections because my work area was not the best enviroment to be painting to start with, outside, under cover, hope it don't rain type of fun. I used enamel and it is still in great shape evenafter year or so. Hope this helps |
marvin pack (Gomer)
Registered Member
Username: Gomer
Post Number: 73
Registered: 3-2007
Posted From: 76.4.136.26
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 11, 2007 - 6:08 pm: | |
Oh the primer is self-etch and It has become a standard in all paint shops and works with steel also. I also used regular filler to smooth out kinks and dents and primed it just like normal. If you have a problem with the primer sticking wash it with white vinager of all things and that will take any acid off |
Bob Shafer (Michigander_bob)
Registered Member
Username: Michigander_bob
Post Number: 36
Registered: 2-2005
Posted From: 68.61.134.126
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 11, 2007 - 7:22 pm: | |
I used a etching primer called etch fill on my bus. used it on galvanized steel and aluminum.no problems at all. your paint supplier should have an etching primer in stock...
Bob |
Gus Causbie (Gusc)
Registered Member
Username: Gusc
Post Number: 433
Registered: 11-2005
Posted From: 63.97.117.23
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 11, 2007 - 11:10 pm: | |
Jim,
Ditto to the etching. Don't use zinc chromate, it is a great anti corrosive paint but not a good primer. |
Jim Huskins (Lostranger)
Registered Member
Username: Lostranger
Post Number: 2
Registered: 8-2007
Posted From: 72.71.83.123
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 12, 2007 - 8:43 pm: | |
Thanks for the input. I'm going to the ICI paint store tomorrow for etch and fill primer. I'm still planning to camfer the joints between the extruded panels a bit with a sander and fill with body filler unless someone has tried this and found that it broke loose later.
Best regards, Jim |
Gus Causbie (Gusc)
Registered Member
Username: Gusc
Post Number: 437
Registered: 11-2005
Posted From: 63.97.117.15
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 12, 2007 - 9:53 pm: | |
Jim,
I would hesitate to fill between panels because Al moves so much when heating or cooling.
I see no problem filling small holes on the panels though, just keep the filler as thin as possible. |
Paul Lawry (Dreamscape)
Registered Member
Username: Dreamscape
Post Number: 93
Registered: 5-2007
Posted From: 70.103.23.130
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 13, 2007 - 7:08 am: | |
If you use any body filler, get the stuff that has fiberglass strands in it. Works better than the regular bondo. I can't remember the name, any auto paint store should have it.
Paul |
Hobie (Hobie)
Registered Member
Username: Hobie
Post Number: 2
Registered: 8-2007
Posted From: 76.176.191.171
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 13, 2007 - 11:16 am: | |
Gus is right. First you zinc chromate on the bare alum(thin coat)then you use a filler/primer for the sand scratches in the bondo. Get the epoxy primer. It sands easier and fills great.
Urge you to not use bondo to fill the seams. Between the thermal expansion and vibration it will develop a crack.
To prevent this you must weld them first, then use bondo to smooth the joint.
Short of that use a good paintable caulk designed for auto body use. That will allow flexing and hold your paint.
Regarding your pinholes. Drill them out larger to remove the addn'l corrosion. Grind the area with 36 grit. Bondo needs this 'tooth' and the primer will take care of the smoothing later. Good Luck! |
george bruton (Tazman632000)
Registered Member
Username: Tazman632000
Post Number: 29
Registered: 2-2007
Posted From: 65.184.183.4
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 15, 2007 - 8:47 am: | |
been painting aluminum for years on boat stuff. dupont makes a very good self ecthing zinc chromate primer 2 part called vari prime. ive used it on my towboats as a primer for years in saltwater enrivoment with great results. im going to be using dupont nasons 2 part primer when i paint the outside of my 4106. you have 4 days after put it on to apply the top coat |
Gus Causbie (Gusc)
Registered Member
Username: Gusc
Post Number: 444
Registered: 11-2005
Posted From: 63.97.117.31
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 15, 2007 - 6:27 pm: | |
George,
Sounds as if zinc chromate has been greatly improved since I used it very much.
Is this an epoxy, must be if it is two-part? |
george bruton (Tazman632000)
Registered Member
Username: Tazman632000
Post Number: 30
Registered: 2-2007
Posted From: 65.184.183.4
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 15, 2007 - 8:38 pm: | |
yes its a 2 part. we paint our bare aluminum super structures on our towboats with it then topcoat right away with paint like imron or alwgrip does a good job. it does not get quite a hard as some of the other 2 parts so its easy to sand if you have too. |
Jim Huskins (Lostranger)
Registered Member
Username: Lostranger
Post Number: 10
Registered: 8-2007
Posted From: 72.71.71.72
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 20, 2007 - 6:19 am: | |
I REALLY appreciate this discussion. I will abandon plan to fill the panel seams. I've not selected a primer or filler yet, but I've not had time to go to the stores and ask questions. Should be back on the paint project this week.
Jim |