Getting some hairline size sealant separation on upper side of a window

Need some kind of White sealant to touch up. What product should I look for?

Get some Sista F-134 High Elastic Acrylic Sealant (White). I use it around many of my windows after the regular silicone just failed to do the job. The high elasticity is a plus. The F-134 is also paintable....takes about 24 hours to fully dry...but it's touch dry after an hour or so. Available in Thai hardware stores like Homepro, Global, etc. You won't have any problem finding it in these types of stores. Costs around Bt150 per tube.

The reason it is pulling apart is the sealant is applied in the wrong shape. When shaped in an hour glass the sealant can get close to 200% elongation. The key is to put some backer rod in first to allow the sealant to have the correct shape on the back. They sell backer rod in 100 meter rolls at watsadu, global, etc. Then apply sealant with the proper shape on the front.