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Primer Question

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vernon.franklin(at)gmail.
Guest

Posted: Tue Aug 17, 2010 3:49 am Post subject: Primer Question

I have been using Alumiprep, Alodine, and AKZO on the parts so far.  Since I cannot soak the skins in anything large enough, I have ended up just washing them with Alumiprep and Alodine with a Brillo sponge on top of a saw horse.  I noticed another builder's site the other day, and he appeared to just take a sander to the inside of the skins to scuff them up before priming.  

 



Is there a preferred technique to preparing the large skins for priming?  

Is sanding better than the chemical wash?

Does sanding cause structural harm to the skins?

 -- 

Vernon Franklin



  [quote][b]

daveleikam(at)wi.rr.com
Guest

Posted: Tue Aug 17, 2010 4:40 am Post subject: Primer Question

Save the weight, don't prime the skins  

  

 Dave Leikam

 [quote]   ---

pitts_pilot(at)bellsouth.
Guest

Posted: Tue Aug 17, 2010 4:55 am Post subject: Primer Question

OMG!!!  He said it!!!!  The first shot's been fired.  WW3 is sure to follow!!     

 Linn ...... slow morning .....

 

 

 

 Dave Leikam wrote: [quote]            Save the weight, don't prime the skins 

    

   Dave Leikam

    	  Quote: 	
		       ----- Original Message ----- 

     From:     Vernon Franklin (vernon.franklin(at)gmail.com) 

     To:     rv10-list(at)matronics.com (rv10-list(at)matronics.com) 

     Sent: Tuesday, August 17, 2010 6:47 AM

     Subject: Primer Question

     

     

     I have been using Alumiprep, Alodine, and AKZO on the parts so far.  Since I cannot soak the skins in anything large enough, I have ended up just washing them with Alumiprep and Alodine with a Brillo sponge on top of a saw horse.  I noticed another builder's site the other day, and he appeared to just take a sander to the inside of the skins to scuff them up before priming.  

     

     

     Is there a preferred technique to preparing the large skins for priming?  

     Is sanding better than the chemical wash?

     Does sanding cause structural harm to the skins?

     

     

 -- 

 Vernon Franklin

     

      	  Quote: 	
		  



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 [b]

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Tue Aug 17, 2010 4:55 am Post subject: Primer Question

Lots of archives to review on topic. The one item you want to get rid

of, is the brillo pad, if that is what you are using. It is of steel

wool, which will induce corrosion in aluminum. Scotchbrite pads are

what are used most commonly, with or without alumiprep.



On Tue, Aug 17, 2010 at 4:47 AM, Vernon Franklin

<vernon.franklin(at)gmail.com> wrote:

 	  Quote: 	
		   I have been using Alumiprep, Alodine, and AKZO on the parts so far.  Since I

 cannot soak the skins in anything large enough, I have ended up just washing

 them with Alumiprep and Alodine with a Brillo sponge on top of a saw horse.

  I noticed another builder's site the other day, and he appeared to just

 take a sander to the inside of the skins to scuff them up before priming.

 Is there a preferred technique to preparing the large skins for priming?

 Is sanding better than the chemical wash?

 Does sanding cause structural harm to the skins?

 --

 Vernon Franklin

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD

philperry9(at)gmail.com
Guest

Posted: Tue Aug 17, 2010 4:55 am Post subject: Primer Question

I use a vibrating sanders over the top of a scotchbrite pad.  Works really well to scuff the surface.  Actually sanding the surface might be a bit overkill. 

Then I rinse it with a solvent like ppg's dx-330.  Then alodine and/or prime.   

Works fine.  

On Aug 17, 2010 6:53 AM, "Vernon Franklin" <vernon.franklin(at)gmail.com (vernon.franklin(at)gmail.com)> wrote:> I have been using Alumiprep, Alodine, and AKZO on the parts so far.  Since I

 > cannot soak the skins in anything large enough, I have ended up just washing

 	  Quote: 	
		   them with Alumiprep and Alodine with a Brillo sponge on top of a saw horse.

  I noticed another builder's site the other day, and he appeared to just

 > take a sander to the inside of the skins to scuff them up before priming.

 	  Quote: 	

 Is there a preferred technique to preparing the large skins for priming?

 Is sanding better than the chemical wash?

 > Does sanding cause structural harm to the skins?

[quote] 

 -- 

 Vernon Franklin

   	  Quote: 	
		  [b]

rbibb

Joined: 16 Jul 2009
Posts: 37

Posted: Tue Aug 17, 2010 6:03 am Post subject: Primer Question

One thing I didn’t know until I talked to an industrial painter on another topic was that you should not alodine and then Prime if you are using an etching primer (wash primer).  If you alodine then use no primer or epoxy primer.  If using wash primer ( self-etching) the skip the alodine totally and just clean before priming.  

   

I’m using a combo of methods depending on what part of the airframe I’m dealing with.  I don’t alodine unless I can immerse the part in the tank.  Wiping on can’t insure good coverage.  

     

Richard Bibb  

   

        

  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Vernon Franklin

 Sent: Tuesday, August 17, 2010 6:48 AM

 To: rv10-list(at)matronics.com

 Subject: Primer Question  

  

     

I have been using Alumiprep, Alodine, and AKZO on the parts so far.  Since I cannot soak the skins in anything large enough, I have ended up just washing them with Alumiprep and Alodine with a Brillo sponge on top of a saw horse.  I noticed another builder's site the other day, and he appeared to just take a sander to the inside of the skins to scuff them up before priming.    

    

   

    

Is there a preferred technique to preparing the large skins for priming?    

    

Is sanding better than the chemical wash?  

    

Does sanding cause structural harm to the skins?  

    

   

  

-- 

 Vernon Franklin   	  Quote: 	
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       [quote][b]

drfred(at)suddenlinkmail.
Guest

Posted: Tue Aug 17, 2010 7:25 am Post subject: Primer Question

I used a Scotchbrite pad before the alumiprep.  I would think sanding 

would be too aggressive and might leave sandpaper residue behind. 



Dr Fred



Vernon Franklin wrote:

 	  Quote: 	
		   I have been using Alumiprep, Alodine, and AKZO on the parts so far. 

  Since I cannot soak the skins in anything large enough, I have ended 

 up just washing them with Alumiprep and Alodine with a Brillo sponge 

 on top of a saw horse.  I noticed another builder's site the other 

 day, and he appeared to just take a sander to the inside of the skins 

 to scuff them up before priming.  



 Is there a preferred technique to preparing the large skins for priming?  

 Is sanding better than the chemical wash?

 Does sanding cause structural harm to the skins?



 -- 

 Vernon Franklin



 *

 *

AV8ORJWC

Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"

Posted: Tue Aug 17, 2010 7:39 am Post subject: Primer Question

Sanding removes a percentage of the pure aluminum protective coating. Sanding is not better than correct chemical preparation - only an alternate.  It does increase Adhesion but most builders can forget that the Alclad is only 5% of the base metal covering per side and burn through to the copper alclad. That is all too common with the RV-12 skins. Many forget how thin their skin is and sand beyond the pure aluminum outer coating in a flash.  Others get simple blemishes during the build and try to scotchbrite them away (so their friends don't see) - taking the pure aluminum down in the process.  Best bet,  Leave all the chemistry and abrasion to the painter or your chosen process.  Know your topcoat and the recommended prep chemistry.

  

 The RV-10 does not have the same ability to be polished for decades like a DC-3 (they are just a tad bit thicker).  It can be polished, but each effort removes oxidation (pure aluminum oxide) in the effort for a Nuvite Mirror Finish.

  

 The primer used should always be compatible with the topcoat that follows.  Primer by definition has its own chemical adhesion characteristic and is porous so that it bonds with the topcoat properly applied at the final stage.  Primer left without topcoat absorbs hydrocarbons, dust, and moisture setting up an entirely different experience.  Some will retort they use a Primer/Sealer and so "They have escaped the first bullet".

  

 Numerous early RV-10 builders watched as their primer failed to adhere to their improperly prepared surfaces.  Others watch as the topcoat delaminates upon rain or ice experiences over years of investment.  One painter at our field who has won numerous award winning RV paint jobs uses the sandpaper and pneumatic orbital to insure bonding.  He doesn't expect to see returns for repaint and eliminates the possibility of the owner ever chemically stripping the topcoat and hand polishing during the skin's life.  What you don't see won't hurt you... Right?  I cringe everytime I see it.  I know that he is keeping repaint to a minimum, but ouch!

  

 Alodine is a two step chemical surface prep which etches with acid (Phosphoric) then converts with another acid (Chromic) to harden the soft, pure aluminum.  It is a "Hazmat" and needs to be used by an educated operator.  The sealed porosity aides in primer adhesion and topcoats which follow.  Some warbirds and many certificated production amphibs use it judiciously.

  

 As Kelly said, under no circumstance should a metallic sponge be applied so let the volley's return....

  

 I used tap water once to wash off a really large prepped area.  Ten years later the paint began to shed its adhesion due to hard water deposits under and above the primer. So follow the correct chemistry.  Painting can give lots of satisfaction, endless frustration and no credit towards 51%, so many choose wisely on which side of the skirmish to lob their volley.

  



  John Cox

 Part-time airline painter and former custom car refinisher before I got smart.



  

 Do not Archive

  From: owner-rv10-list-server(at)matronics.com on behalf of Vernon Franklin

Sent: Tue 8/17/2010 4:47 AM

To: rv10-list(at)matronics.com

Subject: Primer Question

  I have been using Alumiprep, Alodine, and AKZO on the parts so far.  Since I cannot soak the skins in anything large enough, I have ended up just washing them with Alumiprep and Alodine with a Brillo sponge on top of a saw horse.  I noticed another builder's site the other day, and he appeared to just take a sander to the inside of the skins to scuff them up before priming.  

 



 Is there a preferred technique to preparing the large skins for priming?  

 Is sanding better than the chemical wash?

 Does sanding cause structural harm to the skins?

 



-- 

Vernon Franklin



[quote]


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[b]

pitts_pilot(at)bellsouth.
Guest

Posted: Tue Aug 17, 2010 7:54 am Post subject: Primer Question

I'm going to chime in here ..... The good Dr. is correct .... sanding 

can be aggressive ..... it just depends on the grit.  The thin pure 

aluminum coating (the alclad part) is very thin ..... and going through 

it decreases the sheets natural ability to stay corrosion free.  If you 

use an 'aluminum brightener' no matter what the brand, flush well with 

water, dry, and apply alodine with a fine grit pad .... like a green 

one, not red.  Once you have applied a coat of alodine with the pad, use 

a rag soaked in alodine to keep the surface wet.  Do not allow the 

alodine to dry.  Once you've met the time restraints .... some solutions 

can be stronger than others and take less time .... again rinse with 

water and dry. That's just about all you can do on a large sheet.  If 

it's a small piece, then submerge it in the alodine without doing the 

pad steps.  As someone else stated, you gain nothing by alodine AND 

self-etching primer.  One or the other, but the prep is the same.  Keep 

in mind that the primer weighs more than the alodine.  'Nuff said.

Linn

Fred Williams, M.D. wrote:

 	  Quote: 	

 <drfred(at)suddenlinkmail.com>

 I used a Scotchbrite pad before the alumiprep.  I would think sanding 

 would be too aggressive and might leave sandpaper residue behind.

 Dr Fred

 Vernon Franklin wrote:

> I have been using Alumiprep, Alodine, and AKZO on the parts so far. 

>  Since I cannot soak the skins in anything large enough, I have ended 

> up just washing them with Alumiprep and Alodine with a Brillo sponge 

> on top of a saw horse.  I noticed another builder's site the other 

> day, and he appeared to just take a sander to the inside of the skins 

> to scuff them up before priming. 

> Is there a preferred technique to preparing the large skins for 

> priming?  Is sanding better than the chemical wash?

> Does sanding cause structural harm to the skins?

>

> -- 

> Vernon Franklin

>

> *

> *

wgreenley

Joined: 09 Jan 2010
Posts: 100
Location: Dowagiac, MI

Posted: Tue Aug 17, 2010 8:48 am Post subject: Primer Question

Just watched 'From the Group Up' the TV series. On it they use an aggressive

sanding for paint prep and to eliminate scratches and smooth the surface.

 	  Quote: 	
		  From what I am reading that sounds way to aggressive or are people

comfortable with that amount of sanding. For those who haven't seen, they
	


use a power sander 220 grist, 320 grit I think, followed by scotch bright.

Bill



--

rv10builder(at)verizon.ne
Guest

Posted: Tue Aug 17, 2010 11:06 am Post subject: Primer Question

For the EAA members out there, Ron Alexander did a webinar on painting, he 

covers this topic pretty well.

http://www.eaavideo.org/video.aspx?v=83414708001

Pascal



--------------------------------------------------

From: "William Greenley" <wgreenley(at)gmail.com>

Sent: Tuesday, August 17, 2010 9:46 AM

To: <rv10-list(at)matronics.com>

Subject: RE: Primer Question



[quote] 



 Just watched 'From the Group Up' the TV series. On it they use an 

 aggressive

 sanding for paint prep and to eliminate scratches and smooth the surface.

>From what I am reading that sounds way to aggressive or are people

 comfortable with that amount of sanding. For those who haven't seen, they

 use a power sander 220 grist, 320 grit I think, followed by scotch bright.

 Bill



 --

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Tue Aug 17, 2010 12:33 pm Post subject: Primer Question

Well, I know that 1950s and 60s Cessnas had neither any scuffing or 

alodine, as you could read the labels on the skins when you stripped the 

paint of. As near as I could tell they were simply sprayed with zinc 

chromate and the finish acrylic enamel as they left the factory, with 

zero primer on the inside of the skins. Only 50 years later are they 

beginning to show some corrosion, except for those that lived in 

corrosive atmosphere near a coast. I don't know about other builders, 

but I certainly don't expect to have to worry in the 15-20 years I might 

be able to fly my creation if the medical holds.

On 8/17/2010 9:46 AM, William Greenley wrote:

[quote] 



 Just watched 'From the Group Up' the TV series. On it they use an aggressive

 sanding for paint prep and to eliminate scratches and smooth the surface.

 > From what I am reading that sounds way to aggressive or are people

 comfortable with that amount of sanding. For those who haven't seen, they

 use a power sander 220 grist, 320 grit I think, followed by scotch bright.

 Bill



 --

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

johngoodman

Joined: 18 Sep 2006
Posts: 530
Location: GA

Posted: Thu Aug 19, 2010 7:11 am Post subject: Re: Primer Question

Corrosion X

_________________
#40572 Phase One complete in 2011

pitts_pilot(at)bellsouth.
Guest

Posted: Thu Aug 19, 2010 8:14 am Post subject: Primer Question

Corrosion X is expensive.  Get Boeshield by the gallon and cut it with 

mineral spirits.

Linn



johngoodman wrote:

 	  Quote: 	
		   



 Corrosion X



 --------

 #40572 QB. Working on Cowling &amp; Panel

 N711JG reserved





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