My house was built in 2008 using Hardie Board siding (Mountain Sage color). Caulking of the same color was used at all joints and corners. Over the months and exposure to the elements (mainly UV rays from the sun is my guess), the thinest/end portion of the caulking on the Hardie Board is now showing a whitish hue. The Hardie Board manufacturer, the reseller and the house builder have no idea what has caused this "hue" or how to safely remove it without damaging the factory painted board.
I tried rubbing Murphy's Soap oil on these "hue" spots and it seemed to work for a few months but they are now reappearing.
Is there any safe stain remover for this "hue" (so as not to damage the factory paint color) or do I need to use matching touch-up paint over all these whitish hue marks?
Thanks!

Was the caulk supplied by the Hardie Company?

The caulking was supplied by Holden Humphrey Co. in Easthampton, MA. They are probably the supplier of caulking for all Hardie Company composite siding.

The caulking was supplied by Holden Humphrey Co. in Easthampton, MA. They are probably the supplier of caulking for all Hardie Company composite siding.

Sorry for the delay in responding... am not familiar with the way it's done... hope you get this response.

That's my problem, too.. It's frustrating right?

But somehow I gathered some reliable info regarding that by watching a video at http://www.dailymotion.com/video/xeh96c_siding-repair-houston-8665935222_people

Try it.. Hope it helps :)

Sounds like the caulk is fading. The very thin portions do not have enough pigment to kee the UV from fading the caulk.