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.

  #1  
Old 04-03-2021, 11:07 AM
bill.hutchison bill.hutchison is offline
 
Join Date: May 2020
Location: Northern VA
Posts: 178
Default Paint Cracking in a few places

https://photos.google.com/share/AF1Q...ItdVNSYnBRZGdn

I've noticed a few places on my RV where the paint is cracking a bit. This spot is right by the oil door in the cowl, but there are a couple other places as well.

What's the best way to remedy this? She's an older bird and she's got some mileage on her, but I'd like to try and keep her looking tip-top.
Reply With Quote
  #2  
Old 04-03-2021, 07:02 PM
wawrzynskivp wawrzynskivp is offline
 
Join Date: Feb 2018
Location: san jose
Posts: 41
Default Cracks

Hello,

What I see there is shrinkage of filler. Most likely polyester like bondo. Grind, prep and resurface with an epoxy filler to achieve the same height without the poly shrink problems/


Vince
Reply With Quote
  #3  
Old 04-04-2021, 07:31 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,958
Default

Quote:
Originally Posted by wawrzynskivp View Post
Hello,

What I see there is shrinkage of filler. Most likely polyester like bondo. Grind, prep and resurface with an epoxy filler to achieve the same height without the poly shrink problems/


Vince
polyester filler is the standard in auto body repair and has been used on millions of repairs. Yes it shrinks a very small amount in the first 30-90 days and is then VERY stable over time.
What is seen here is NOT filler shrinkage.

That door is likely polyester based fiberglass layup from an old kit. This is crazing/cracking from the polyester based resin becoming hard and brittle as it gives up it's plasticizers over the decades. Pretty sure this is why Vans went to epoxy or vynal ester based F/G parts to avoid this, as those materials don't have that problem.

It can't really be repaired effectively, as it will continue to crack and telegraph through most repair attempts, Unless you can get layers of new cloth over it. Once the parts are dry and brittle, the stability is gone. This is an inherent flaw in thin polyester resin layups; They don't age well.

Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 04-04-2021 at 07:49 AM.
Reply With Quote
  #4  
Old 04-04-2021, 07:29 PM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 9,935
Default

I think you're both right, sorta. $10 says it was sprayed with K200, or Featherfill, or similar polyester primer/surfacer.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #5  
Old 04-05-2021, 05:08 AM
bill.hutchison bill.hutchison is offline
 
Join Date: May 2020
Location: Northern VA
Posts: 178
Default

Quote:
Originally Posted by DanH View Post
I think you're both right, sorta. $10 says it was sprayed with K200, or Featherfill, or similar polyester primer/surfacer.
Hmm. I'm not sure what the OB (original builder) did in that respect but it certainly sounds plausible.

If it can't really be repaired effectively unless new cloth is in there...are you/Larry saying it has to be sanded down to cloth all the way, or actually cut out and re-fiberglas'd?

-b
Reply With Quote
  #6  
Old 04-05-2021, 06:19 AM
DanH's Avatar
DanH DanH is offline
 
Join Date: Oct 2005
Location: 08A
Posts: 9,935
Default

Quote:
Originally Posted by bill.hutchison View Post
Hmm. I'm not sure what the OB (original builder) did in that respect but it certainly sounds plausible.

If it can't really be repaired effectively unless new cloth is in there...are you/Larry saying it has to be sanded down to cloth all the way, or actually cut out and re-fiberglas'd?
When you're ready to refinish, slide a knife blade up under a few of those chips. If the chip is thin, the backside is uniform gray or dark mustard, and they pop off the surface leaving bare glass, it's a primer-surfacer problem.

The fix starts with the one fiberglass task I despise, sanding back to bare glass. Anyone know a safe way to remove paint and primer from fiberglass, other than sanding?
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Reply With Quote
  #7  
Old 04-05-2021, 09:06 AM
9GT's Avatar
9GT 9GT is offline
 
Join Date: Jan 2010
Location: Southern Michigan
Posts: 2,105
Default

Quote:
Originally Posted by DanH View Post
The fix starts with the one fiberglass task I despise, sanding back to bare glass. Anyone know a safe way to remove paint and primer from fiberglass, other than sanding?
I had to rebuild the fiberglass nose bowl on my C-152. It was cut up real good from from the spinner due to sagging motor mounts, and camloc's that wore through the fiberglass. I had real good luck using the old fashioned Kleen-Strip Aircraft paint stripper,,,(not the newer low VOC stuff they sell now). Doing small sections at a time I was able to carefully monitor the dwell time and get the paint and stripper off leaving solid fiberglass where the paint was.
Still involved lots of sanding to get to the point of patching and re-painting.
__________________
David C.
Howell, MI
RV-10: #41686 Under Construction
RV-9A: #90949 Under Construction
RV-10: #40637 Completed/Sold 2016
Cozy MKIV:#656 Completed/Sold 2007
"Donor Exempt" but donated through Dec. 2021
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 07:33 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.