VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.






VAF on Twitter:
@VansAirForceNet

  #1  
Old 11-27-2022, 11:04 AM
Wayne Stambaugh Wayne Stambaugh is offline
 
Join Date: Nov 2011
Location: Montgomery, Alabama
Posts: 11
Default Bead Blasting/ Etch Primer

Im familiar with the large number of products to prep aluminum previous to painting and Im not excited about using any of them. Im working on an RV14 and not planning to prime or paint everything but where parts are joined together (aileron brackets, flap brackets, rib to spar, etc) Im thinking about lightly bead blasting those areas and priming them with SEM etch primer. The surface left from the bead blasting supposedly relieves stress in the metal and takes small scratches away. As far as adhesion is concerned a bead blasted surface certainly has more tooth to it than most other treatments. Anyone tried it?
Reply With Quote
  #2  
Old 11-27-2022, 11:58 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,565
Default

Probably best NOT to bead blast the surfaces. Successful priming is achieved without that, with no damage to the alclad surface or the fairness of the part.

All you need is maroon Scotchbrite to abrade the surface and some suitable solvent to clean it. I've used lacquer thinner, denatured alcohol and isopropyl alcohol successfully for that, along with SEM, a couple of rattlecan zinc chromate or phosphate primers and Stewart EkoPoxy. Of those, the SEM and the EkoPoxy are the best.

The thread on Primers covers a multitude of opinions and comments and is worth reading.

Dave
Reply With Quote
  #3  
Old 11-27-2022, 12:11 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 8,042
Default

Quote:
Originally Posted by Wayne Stambaugh View Post
I’m familiar with the large number of products to prep aluminum previous to painting and I’m not excited about using any of them. I’m working on an RV14 and not planning to prime or paint everything but where parts are joined together (aileron brackets, flap brackets, rib to spar, etc) I’m thinking about lightly bead blasting those areas and priming them with SEM etch primer. The surface left from the bead blasting supposedly relieves stress in the metal and takes small scratches away. As far as adhesion is concerned a bead blasted surface certainly has more “tooth” to it than most other treatments. Anyone tried it?
No stress in hardened / tempered aluminum or un-hardened 6061-O for that matter; Not dealing with cast iron or welded steel here. I would NOT use bead blasting. Simple maroon pad (320-400 grit). If you want more tooth, use 220 grit sandpaper. Two coats of most epoxy primer will fully cover those scratches. No need for self etch primer if you are mechanically etching the metal (i.e. sanding or scuffing). Most painters don't like the acid left behind with self-etch; Problematic for adhesion of the next coat.
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 11-27-2022 at 12:20 PM.
Reply With Quote
  #4  
Old 11-27-2022, 12:29 PM
rocketbob's Avatar
rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,879
Default

It is more important the interior surfaces are covered with some sort of primer or paint, doesnt matter if its etching although etching would be better. If you saw all of the corroded interior surfaces I find on airplanes I work on, some even relatively new, even experimentals...you would prime everything. You dont need to be near the oceans. In fact the large temperature swings as one encounters in the midwest will cause corrosion. I have literally seen wings dripping wet on the inside after a prolonged cold and sudden humid warmup.
__________________

Please don't PM me! Email only!

Bob Japundza CFII A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Reply With Quote
  #5  
Old 11-27-2022, 01:19 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 11,229
Default

Bead blasting sheet aluminum tends to make it warp, and it removes the pure aluminum layer on alclad. Don't do it.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #6  
Old 11-27-2022, 01:37 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 3,279
Default

Quote:
Originally Posted by rocketbob View Post
It is more important the interior surfaces are covered with some sort of primer or paint, doesnt matter if its etching although etching would be better. If you saw all of the corroded interior surfaces I find on airplanes I work on, some even relatively new, even experimentals...you would prime everything. You dont need to be near the oceans. In fact the large temperature swings as one encounters in the midwest will cause corrosion. I have literally seen wings dripping wet on the inside after a prolonged cold and sudden humid warmup.
Interesting. My 1957 C-172 lived a hard life between being tied down outside and being hangared in northern Wisconsin, Illinois, and SE Indiana. It was not primed and showed little to no corrosion over the 20 years I owned it
__________________
Bob
EAA Tech Counselor
Aerospace Engineer '88

RV-10-ER
N464RL
In Paint at Evoke!
Garmin G3X-T, Barrett EFII S32, CAI, MTV-9B

Dues+ Paid 2022,...Thanks DR+
Reply With Quote
  #7  
Old 11-27-2022, 06:27 PM
rocketbob's Avatar
rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,879
Default

Quote:
Originally Posted by rocketman1988 View Post
Interesting. My 1957 C-172 lived a hard life between being tied down outside and being hangared in northern Wisconsin, Illinois, and SE Indiana. It was not primed and showed little to no corrosion over the 20 years I owned it
What you are describing is impossible. I have a 150 that's spent most of its life in hangars in Indiana and there is a fair amount of corrosion in the wings.
__________________

Please don't PM me! Email only!

Bob Japundza CFII A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Reply With Quote
  #8  
Old 11-27-2022, 09:15 PM
Wayne Stambaugh Wayne Stambaugh is offline
 
Join Date: Nov 2011
Location: Montgomery, Alabama
Posts: 11
Default Always a disagreement

I should have known how this was going to end up. Primer wars, however thanks for everyones input.
Reply With Quote
  #9  
Old 11-27-2022, 09:42 PM
moosepileit moosepileit is offline
 
Join Date: Dec 2010
Location: Louisville, KY
Posts: 865
Default

Depending on sun angle, drainage slopes and insulation or lack, ventilation or lack, the same two planes in two separate hangars can have totally different exposures. I've seen nice air, high and dry in one and around the corner facing opposite another hangar is almost raining inside.
__________________
RV-6, bought from builder.
O-320, slider, carb, mags, FP
Reply With Quote
  #10  
Old 11-28-2022, 07:56 AM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 3,279
Default Really

Quote:
Originally Posted by rocketbob View Post
What you are describing is impossible. I have a 150 that's spent most of its life in hangars in Indiana and there is a fair amount of corrosion in the wings.
We will have to agree to disagree. Pretty sure I know the airplane after owning it for 20 years
__________________
Bob
EAA Tech Counselor
Aerospace Engineer '88

RV-10-ER
N464RL
In Paint at Evoke!
Garmin G3X-T, Barrett EFII S32, CAI, MTV-9B

Dues+ Paid 2022,...Thanks DR+
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:43 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.