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08-11-2017, 04:35 PM
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#1
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Prepping for roof paint
I'm in the process of prepping for roof paint. I have stripped and sanded the areas of the roof I wish to paint.
Now that I'm down to bare aluminum do I need to prep the aluminum, with Alodine solution? I was thinking all I need to do next is wiped down with lacquer thinner and roll on my epoxy primer. My plan is to add these insulating beads to the primer and topcoat.
Also should I renew all my seam sealants? Will the paint stick to it sufficiently? Or is it better to scrape sealants, and reapply after painting?
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08-11-2017, 05:45 PM
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#2
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Rivet Master
2002 30' Classic S/O
Fleming Island
, Florida
Join Date: Nov 2013
Posts: 4,667
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I don't know if this is correct, but I would seal before painting. As to aluminum treatment, I would go with whatever your paint system recommends.
Al
__________________
You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO WBCCI 1322
2002 Classic 30 Slideout -S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins
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08-12-2017, 05:22 AM
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#3
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Thanks for the reply Al, For the seams I'm gonna seal and paint then seal again. I can't stand a leak, especially when it leads to rotting floors!
The Aircraft paint I have doesn't have any prep directions with it, only mixing instructions. I guess I'll just clean the skin with acetone and paint.
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08-12-2017, 06:45 AM
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#4
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Rivet Master
1994 30' Excella
Mississauga
, Ontario
Join Date: Jun 2004
Posts: 1,234
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there are primers that are specifically formulated for aluminum. I would look into using one for peace of mind.
Al
__________________
Al and Jean
TAC ON-3
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08-12-2017, 07:07 AM
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#5
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Hi Al, I do have the primer for aluminum, what's your take on prep for the skin is an acetone or lacquer thinner wipe down sufficient?
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08-12-2017, 07:57 AM
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#6
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Rivet Master
1994 30' Excella
Mississauga
, Ontario
Join Date: Jun 2004
Posts: 1,234
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I would think so. Just make sure it is clean. If you sanded it and then cleaned it so there is no grease or dust you should be good to go. I used a ceramic based paint on my roof and it made a huge difference on heat load.
Al
__________________
Al and Jean
TAC ON-3
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08-12-2017, 07:58 AM
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#7
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Rivet Master
1977 31' Sovereign
Vintage Kin Owner
Vintage Kin Owner
Sunset Valley
, Texas
Join Date: Jul 2016
Posts: 744
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It is best to scumble bare aluminum with an aggressive scotch bright pad.
Get the red ones from a good auto paint store. Don't skip or skimp on this step as it is necessary for you primer to bond properly.
Ian
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08-12-2017, 08:05 AM
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#8
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Quote:
Originally Posted by BigAl
I would think so. Just make sure it is clean. If you sanded it and then cleaned it so there is no grease or dust you should be good to go. I used a ceramic based paint on my roof and it made a huge difference on heat load.
Al
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Thanks Al, I wash the roof, sanded with 180 grit, washed again, now doing fine details around Rrivet heads and places the sander couldn't get. Just trying to make sure I get this right, it's a big job that I hope not to have to do again. I'm hopeful the thermal solutions product will be all they say it is. Cheers
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08-12-2017, 08:14 AM
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#9
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Quote:
Originally Posted by Iansk
It is best to scumble bare aluminum with an aggressive scotch bright pad.
Get the red ones from a good auto paint store. Don't skip or skimp on this step as it is necessary for you primer to bond properly.
Ian
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Ian, Scotch bright is The bomb! It may be a little overboard, but I came up with this tool to detail around each rivet it goes fairly quick.
I know all good paint job are due to the prep work, and I'm hopeful that my extra work will pay off.
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08-12-2017, 08:41 AM
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#10
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Rivet Master
1986 25' Sovereign
2008 F350, 6.4L diesel
, Oak Harbor, WA
Join Date: Sep 2015
Posts: 605
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You may find this work useful. The method used a material (epoxy based) made for this type of solution:
http://www.airforums.com/forums/f474...ng-156379.html
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08-12-2017, 02:09 PM
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#11
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4 Rivet Member
1973 31' Sovereign
1978 Argosy 30
1985 31' Excella
Sacramento
, California
Join Date: Nov 2016
Posts: 323
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Hmmm.. well... you got the scotch bright down... but I would use a product called alumaprep.... made by dupont and others.. we use it on aircraft... after you seal all the seams... it is not that toxic... but use rubber gloves... when applying it with the scotch bright pad 'ne all... then rense with clear water... and before the water dry's... apply a coat of clear/or other alodine... conversion coating directly to the part... wait for 90 seconds or longer... but not long enough to allow the liquid to dry... and rense with clear water... don't touch it.. let it dry ... once dry... use some zinc cromate primer... don't need to color coat the piece... just enough so that its lightly coated... let dry... then go ahead and paint with your paint that coats alu... such as aircraft paint.. or dupont immron, centari or other PPG paints... I would not use the other junk on the roof... its like adding sand to paint... doesn't work... it ends up to thick... and then you get to do the whole thing over again... You have to remember that alu expands and contracts ALOT... and so the paint has to have something to stick too... alu makes a oxide on its skin that is made to keep things from sticking to it... ie thus we use the alodine for corrosion inhibiting... and the zinc cromate to act as a go between... the alu and the paint... thus the paint then will stick and stay a while longer than just applying the paint by itself..... That is how we do aircraft... although the new kids on the profession.... aircraft are not painted but rather a large sheet decal.. that sticks to the metal and looks like paint... but them their are expensive and hard to handle...
Contact your automotive paint store... as they know what works and doesn't now that several of the auto manufactures have gone to alu body works... that are painted...
Good luck... G.M.... AI&P in aircraft work
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08-12-2017, 02:28 PM
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#12
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3 Rivet Member
1987 34.5' Airstream 345
Auckland
, New Zealand
Join Date: Feb 2014
Posts: 138
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3m-alodine-acryl r-ceramic beads-flex white
Hi Deja Vu,
Looking at the thorough job your doing up there thought I was looking at me on my 345 roof ! That soft alloy down the centre off our roofs once grit sanded, results in removing the mill surf and leaves it vulnerable to oxidization,even under paint that's how it starts to breakdown paint adhesion, so for the small cost in $+T I'm slapping on the Alodine then hose off, Acryl-R 5504C on the seams as this pulls itself back into the small crevices between the sheets as it cures and can be removed without damaging the alloy unlike some urethane products.I have the same vacuum ceramic insulating beads but still looking for a flexible white top coat to mix them in? I wont be using any hard curing paints on that moving roof, a fundamental to keep in mind for me is everything becomes more brittle as it ages. Me included, so Its a trick to get it right this time.
Rus
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08-12-2017, 03:07 PM
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#13
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2 Rivet Member
Currently Looking...
Currently Looking...
White Bear Lake
, Minnesota
Join Date: Jan 2017
Posts: 43
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Bare aluminum will always form a layer of oxide. It is the nature of the beast. Even steel will begin to oxidize immediately if cleaned to a fresh surface. Unfortunately steel continues to oxidize, called rust, until the piece is destroyed. Aluminum stops oxidizing after the initial layer is form unless that layer is disturbed. That disturbance can be physical damage or chemicals. Aluminum exposed to salt, or other chemicals, will continue to create that awful white stuff that is oxide commonly known as corrosion.
A surface preparation such as Alodine is highly recommended for longevity of the aluminum parts.
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08-13-2017, 05:38 AM
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#14
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Quote:
Originally Posted by GM Airstream
Hmmm.. well... you got the scotch bright down... but I would use a product called alumaprep.... made by dupont and others.. we use it on aircraft... after you seal all the seams... it is not that toxic... but use rubber gloves... when applying it with the scotch bright pad 'ne all... then rense with clear water... and before the water dry's... apply a coat of clear/or other alodine... conversion coating directly to the part... wait for 90 seconds or longer... but not long enough to allow the liquid to dry... and rense with clear water... don't touch it.. let it dry ... once dry... use some zinc cromate primer... don't need to color coat the piece... just enough so that its lightly coated... let dry... then go ahead and paint with your paint that coats alu... such as aircraft paint.. or dupont immron, centari or other PPG paints... I would not use the other junk on the roof... its like adding sand to paint... doesn't work... it ends up to thick... and then you get to do the whole thing over again... You have to remember that alu expands and contracts ALOT... and so the paint has to have something to stick too... alu makes a oxide on its skin that is made to keep things from sticking to it... ie thus we use the alodine for corrosion inhibiting... and the zinc cromate to act as a go between... the alu and the paint... thus the paint then will stick and stay a while longer than just applying the paint by itself..... That is how we do aircraft... although the new kids on the profession.... aircraft are not painted but rather a large sheet decal.. that sticks to the metal and looks like paint... but them their are expensive and hard to handle...
Contact your automotive paint store... as they know what works and doesn't now that several of the auto manufactures have gone to alu body works... that are painted...
Good luck... G.M.... AI&P in aircraft work
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GM, thank you for taking the time to write this very informative post. Your experience and detailed instructions will help my process, and peace of mind. Here's a pic of the primer and topcoat I have.
In the sealants section of the form most people recommend Acrylic-R for the seams and small tight areas, I believe that's what the PO had used on the seems previously. When I scraped off the sealant it came off quite easily and remains soft, is that typical for this Acrylic-R ? I have some time expired 890 B1/2 would that be better? Finally, I estimate a half gallon of paint for this area, what would be your guesstimate?
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08-13-2017, 05:42 AM
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#15
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Quote:
Originally Posted by lyleapgmc
Bare aluminum will always form a layer of oxide. It is the nature of the beast. Even steel will begin to oxidize immediately if cleaned to a fresh surface. Unfortunately steel continues to oxidize, called rust, until the piece is destroyed. Aluminum stops oxidizing after the initial layer is form unless that layer is disturbed. That disturbance can be physical damage or chemicals. Aluminum exposed to salt, or other chemicals, will continue to create that awful white stuff that is oxide commonly known as corrosion.
A surface preparation such as Alodine is highly recommended for longevity of the aluminum parts.
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Thanks for your post Lyleapgmc, I am going to order some Aluma prep 33, and Alodine 1201. Just trying to get the best and results that will last, hopefully all the prep work will pay off.
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08-13-2017, 05:48 AM
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#16
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Quote:
Originally Posted by Russell Col
Hi Deja Vu,
Looking at the thorough job your doing up there thought I was looking at me on my 345 roof ! That soft alloy down the centre off our roofs once grit sanded, results in removing the mill surf and leaves it vulnerable to oxidization,even under paint that's how it starts to breakdown paint adhesion, so for the small cost in $+T I'm slapping on the Alodine then hose off, Acryl-R 5504C on the seams as this pulls itself back into the small crevices between the sheets as it cures and can be removed without damaging the alloy unlike some urethane products.I have the same vacuum ceramic insulating beads but still looking for a flexible white top coat to mix them in? I wont be using any hard curing paints on that moving roof, a fundamental to keep in mind for me is everything becomes more brittle as it ages. Me included, so Its a trick to get it right this time.
Rus
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Russell, is the sealant Acrylic-R 5504c from a big box store?? Or is it the one that comes in a can that the airstream suppliers sell?
From my experience, the aircraft paint cures to a hard surface but remains quite flexible. Aircraft undergo a lot of stress from thermal expansion and contraction plus the addition of pressurization cycles.Plus the paint was free, time expired. I like free!
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08-13-2017, 04:54 PM
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#17
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3 Rivet Member
1987 34.5' Airstream 345
Auckland
, New Zealand
Join Date: Feb 2014
Posts: 138
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Hi DV,
Acrylic-R 5504c Thoes are the numbers that are important as there are other Acrylic-R versions less suitable for this purpose.That refillable hand pressure pot system I'v also seen on the Main Airstream web site.What would be extra good about it is that it will deliver at a descent pressure enough force to push the sealer deep between the sheets.
My comments about certain paint's becoming harder over time therefore more brittle leading to cracking peeling ect I guess the trick is to source a high quality paint that has a long flexible life, "look" I'm going to prep my roof properly and am prepared to leave the final coat till I'm satisfied that I'v found the answer to this.
All the prep stuff checks for me by GM .Not sure about aircraft top coat thoe. diff purpose, diff use.
Even a good oil based white top coat with the ceramic's mixed in and hand painted could well be the best, low tech in some areas can be the best answer. I have polished my roof side curved portions,front n rear caps as this looks good from the ground and will also reflect the heat. So no one sees that center long roof panel.What ever I do on my machine it should not be someone elses nightmare down the road, removing old paint included.
Rus
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08-13-2017, 07:06 PM
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#18
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Russell, thanks for your reply, I will be ordering the 5504c in aluminum color from local warehouse. I will be using a foam roller for the roof paint as I don't want to try and spray with the ceramic insulating beads.
On a side note, recon how many 345's are there in Auckland? I personally love the 345's and think they are underrated in value. I love to have one and stick a modern American V8 Diesel duramax engine in it.
Cheers
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08-14-2017, 07:37 PM
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#19
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3 Rivet Member
1987 34.5' Airstream 345
Auckland
, New Zealand
Join Date: Feb 2014
Posts: 138
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Hi DV,# off 345's in NZ = 1 as off 2017.Yes a lot off vehicle for so little money,the thing to remember is a cheap 345 that most parts on them have been consumed by previous owners, baring some replacement bits they have Had done, they really need a slow methodical going through from one end to the other, it's a long way, so if you'v got enough common sense,a little regular money, good practical skills and some free time over time between your normal exciting life then you'll end up with something worth $'s plus a pleasure to use n own and another very fine American Classic cared for.Once refurbished to their original condition they command close to a price off new Throw-away Plastic Motorhome, providing they havn't been butchered to badly we can do a lot off damage very quickly if we just box on without a well thought out n well tested plan, there are a lot off very simple and preventive methods to be known n wise to, but largely the designers/builders off these vehicles over many generations were the very same generation that could get you to the moon n back, they didn't get much wrong in these ol analog machines, all parts fixable and maintainable not throwaway's, but yes some room for modern improvements aswell for sure.
Regarding heavier replacement motor's eg. diesel, the amount off millage has to be considered and times run plus stiffening up front end suspension so you don't loose their good handling by the way off much weightier motor that also needs to be run n maintained eg commercial time as opposed to holiday time so the basic 454 easier cheaper by farrrrrr to be kept healthy.Mine kept up with the traffic on the freeways over there so ummmm.On these forums you can so easily pick up the wrong end off the stick by the badly confused new owners wrongly diagnosing problems and all the misunderstandings get echoed around the forums time and time again.I think your probably at the age where in the very near you'll be fitting electric drive conversions to them, plenty off battery room.
Regarding yu roof, a smooth glossy white to give a good UV and solar heat reflection,and time enough for it to settle out nice n smooth so mold cant get an easy hold.Because we walk on our roofs unlike pilot's I'm thinking soft. Aircraft paint is designed for a specific replacement schedule and if its free well in the end...........
Rus
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09-10-2017, 06:08 AM
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#20
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2 Rivet Member
1992 29' Excella
Powder Springs
, Georgia
Join Date: Aug 2017
Posts: 33
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Well after working like a dog for the last several weeks the roof is painted!! Pictures show after sanding Alumi prep 33 and Alodine 1201.
Sanded and sealed.
Alumiprep 33 and Alodined.
Finally I rolled on two coats of aircraft wing tank primer, it's a two part epoxy paint that also has the Hy-Tech thermal solutions insulating paint additive in it with causes a sand paper like surface.
Ready for top coating which will be rolled on again with more Hy-Tech insulating micro beads.
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