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03-05-2013, 03:07 PM
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#1
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4 Rivet Member
2005 31' Classic
Sunrise Beach
, Missouri
Join Date: Jun 2007
Posts: 252
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Small cracks in Rock Guards
Just noticed that we have several small cracks on the rock guard on the curb side front wrap around window. The cracks are not visible from the outside but we just noticed them today when opening the inside window drape. We do not believe the cracks were caused by rocks because they are too numerous and we have Rock Tamers on our tow vehicle. They are on the lower side of the window that faces the afternoon sun (we have been in Florida nearly four weeks).
Has anyone experienced cracking caused by sun exposure? Except when on the road our Airstream has always been garaged.
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03-05-2013, 03:17 PM
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#2
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Rivet Master
1977 31' Sovereign
1963 26' Overlander
1989 34' Excella
Johnsburg
, Illinois
Join Date: Jul 2005
Posts: 2,944
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I believe the rock guards are made from vacuum formed acrylic sheet. Most of the stress is relieved by the heat during forming but some residual is still there. Acrylic can craze when exposed to some chemicals when it is under internal or external stress. The craze will be more apparent when looking outward. The craze cracks will be perpendicular to the direction of the stress. There is nothing you can do about them but if the break all the way through the plastic, the progression of the crack can be stopped by drilling a small hole at the end of where the crack is progressing.
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03-05-2013, 03:25 PM
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#3
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 20,000
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Cracks or crazing?
Give this a read see if it applies.....I have seen it on AS rock guards.
Bob
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
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03-05-2013, 03:58 PM
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#4
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4 Rivet Member
2005 31' Classic
Sunrise Beach
, Missouri
Join Date: Jun 2007
Posts: 252
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Quote:
Originally Posted by ROBERT CROSS
Give this a read see if it applies.....I have seen it on AS rock guards.
Bob
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There are so many small cracks that appear to be caused more by the sun than any stress. Most of the cracks are less than a quarter of inch and are widely scattered. There are only two larger cracks a little more than one inch long and more than two dozen 1/8" or less widely scattered in a one square foot area. I may call the factory tomorrow to see if anyone has heard about cracks caused by the afternoon sun--it's really weird.
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03-05-2013, 04:49 PM
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#5
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retired USA/USAF
2001 30' Excella
Somerset
, New Jersey
Join Date: Jan 2009
Posts: 2,418
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We also are in Fla. I noticed a crack on the curved stone guard. It's about 3" long and vertical. I when I get home I was planning to drill a small hole at each end and try some nylon mesh and epoxy in an effort to stabilize it. With the smoked finish I think it will be barely visible. Open to any other suggestions along the way.
Thanks all.
__________________
Roger in NJ
" Democracy is the worst form of government. Except for all the rest"
Winston Churchill 1948
TAC - NJ 18
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03-11-2013, 06:43 AM
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#6
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Rivet Master
1977 31' Sovereign
1963 26' Overlander
1989 34' Excella
Johnsburg
, Illinois
Join Date: Jul 2005
Posts: 2,944
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When there are many small cracks that do not go through the total thickness of the plastic that is called "crazing" You can not do much about crazing. As stated before, It is usually caused by chemical exposure to stressed acrylic plastic. The chemicals could be anything from bug spray to some polishes or cleaners. Once you have it, there is no fix. If the cracks extend all the way through the plastic, drilling the holes will stop it from getting worse.
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03-11-2013, 07:21 AM
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#7
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Rivet Master
Currently Looking...
NE
, Indiana
Join Date: Feb 2005
Posts: 620
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We noticed this on our '05 last year, lots of tiny cracks/crazing on both sides of the curved stone guards.
Our trailer is stored inside, so I don't think it has excess UV exposure, but then again, we did have to replace the front skylight that was cracked and leaking this past year.
I used a Rain X spray on wax a couple times, it could be that. Also use formula 303 on the seals.
__________________
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looking for our next AS
TAC IN-3
AIR 7185
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03-12-2013, 12:08 AM
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#8
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4 Rivet Member
2005 31' Classic
Sunrise Beach
, Missouri
Join Date: Jun 2007
Posts: 252
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Quote:
Originally Posted by redeagle313
We noticed this on our '05 last year, lots of tiny cracks/crazing on both sides of the curved stone guards.
Our trailer is stored inside, so I don't think it has excess UV exposure, but then again, we did have to replace the front skylight that was cracked and leaking this past year.
I used a Rain X spray on wax a couple times, it could be that. Also use formula 303 on the seals.
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Your experience sounds very similar to ours. I did clean the windows with Rain X before we left on our trip so that could have been the culprit. We had three days of heavy rain in Florida and we had a small leak in our front skylight. After researching this on the Forum I learned that this is a common problem on OEM skylights and plan to replace both of our skylights when we get home with Maxim skylights recommended as superior by several Forum members, Thanks for your feedback!
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03-12-2013, 01:36 AM
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#9
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Rivet Master
2021 25' Globetrotter
Jamestown
, Rhode Island
Join Date: Mar 2012
Posts: 1,720
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I use this on the acrylic hatches on our boat. Plexus
It seems to have staved off the usual crazing that happens to all boat hatches eventually for 8 years now and the lenses still look very good!
I began using it on the curved stone guards as soon as our Airstream was home. not only does it protect but it cleans and makes them look new....
Bruce
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03-12-2013, 03:30 AM
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#10
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Rivet Master
1977 31' Sovereign
1963 26' Overlander
1989 34' Excella
Johnsburg
, Illinois
Join Date: Jul 2005
Posts: 2,944
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Rainex is a silicone dispersed in a solvent. Both of these components are likely to cause crazing in an acrylic or polycarbonate stressed plastic. Rainex is great for glass windshields and I use it all the time for that, but I would never put it on any plastic parts.
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03-12-2013, 08:46 PM
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#11
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Rivet Master
1987 25' Sovereign
Fort Collins
, Colorado
Join Date: Jan 2010
Posts: 582
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After you stop drill the cracks you can carefully infuse an acrylic glue like Crazy Glue to help strengthen the plexi.
__________________
Alumacoot
“We are confronted with insurmountable opportunities.”
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03-12-2013, 10:22 PM
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#12
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Rivet Master
2015 25' FB Eddie Bauer
2013 25' FB Eddie Bauer
2012 20' Flying Cloud
Small Town
, *** Big Sky Country ***Western Montana
Join Date: Feb 2010
Posts: 2,860
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Dan and Liz's technique has worked for us for years ... standard fix.
__________________
2015 25' Eddie Bauer Int'l FBQ / 2023 Ford Lightning ER
2022 Ford F350 6.2 V-8; equalizer hitch + Shocker air hitch
Honda Eu3200; AIR# 44105; formerly WBCCI 2015.1
Terminal Aluminitis; 2-people w/ 3+ dogs
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03-12-2013, 10:39 PM
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#13
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Rivet Master
2002 19' Bambi
Lafayette
, California
Join Date: May 2005
Posts: 1,567
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One thing to remember about acrylic (or plexiglass) is that it will craze and crack when exposed to alcohol. A typical source of alcohol exposure is window cleaner such as Windex.
Tim
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03-12-2013, 10:57 PM
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#14
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Rivet Master
1965 17' Caravel
1983 27' Excella
Walnut Grove/Laguna Woods
, California
Join Date: Jun 2004
Posts: 1,635
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Plexiglass reacts to Acetone. I removed the curved stone guards on our Excella, put them inside up on a table and applied acetone to the cracks using a syringe with a very fine needle along the cracks. There was also inside damage due to hits on the outside of the guards. Applying acetone seems to have stopped the spreading of that damage.
If you know someone who is diabetic, the disposable syringes they use are perfect for applying acetone for many plastic repairs. The syringes are also plastic, however they do not react to the acetone.
Care must be taken not to smear the wet acetone away from the cracks. If you do damage the inside of the guard in this manner, it may be polished out with tooth paste after all is dry and hard.
This trick was passed on to me by a tech at Vintage Air, a company that makes aftermarket A/C systems for Street Rods and other cars. Their plastic Heat and A/C cases are bonded together using acetone.
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03-13-2013, 06:20 AM
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#15
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4 Rivet Member
2005 31' Classic
Sunrise Beach
, Missouri
Join Date: Jun 2007
Posts: 252
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Quote:
Originally Posted by Jim Foster
Plexiglass reacts to Acetone. I removed the curved stone guards on our Excella, put them inside up on a table and applied acetone to the cracks using a syringe with a very fine needle along the cracks. There was also inside damage due to hits on the outside of the guards. Applying acetone seems to have stopped the spreading of that damage.
If you know someone who is diabetic, the disposable syringes they use are perfect for applying acetone for many plastic repairs. The syringes are also plastic, however they do not react to the acetone.
Care must be taken not to smear the wet acetone away from the cracks. If you do damage the inside of the guard in this manner, it may be polished out with tooth paste after all is dry and hard.
This trick was passed on to me by a tech at Vintage Air, a company that makes aftermarket A/C systems for Street Rods and other cars. Their plastic Heat and A/C cases are bonded together using acetone.
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Thanks for your suggestion for arresting the crazing that has already occured. I will be doing this as soon as we get home next month. Hopefully, information about what was causing the cracking on my stone guards will help other Airstream owners avoid this problem. The expense of replacing stone guards is a major outlay that could be avoided if proper cleaning procedures were understood.
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