Why Water Repellent for Stone Turns Yellow?

[yhchang]

Hello everyone,

I am wondering why some surface water repellents for stone easily turns yellow over time? Is it because of their components reacting with atmosphere or rain?

(I am not sure if it is proper to ask this question here . If not, I will delete it.)

Best regards,
Sam

 

[Lithofin BOB]

Hi - impregnators or sealers can yellow or discolour for a few reasons , some will change the colour of stone or tiles without issue , they simply should be tested prior to completing a complete area.

Incorrect products being used in the wrong situation . i.e.. Some internal sealers used externally can be problematic

Over application of an impregnator or sealer where the discolouration can occur in the over applied polymer or ingredient of the product.

it can also be moisture related, if moisture is trapped behind the seal at installation or if a failure occurs and water penetrates through the back , this can cause water marking /discoloration, rather than you thinking the impregnator or seal is discolouring.

there are some products still out there that are affected by UV and can yellow.

 

[yhchang]

Hi - impregnators or sealers can yellow or discolour for a few reasons , some will change the colour of stone or tiles without issue , they simply should be tested prior to completing a complete area.

Incorrect products being used in the wrong situation . i.e.. Some internal sealers used externally can be problematic

Over application of an impregnator or sealer where the discolouration can occur in the over applied polymer or ingredient of the product.

it can also be moisture related, if moisture is trapped behind the seal at installation or if a failure occurs and water penetrates through the back , this can cause water marking /discoloration, rather than you thinking the impregnator or seal is discolouring.

there are some products still out there that are affected by UV and can yellow.

I see. In above photo, this water repellent has been applied over around 20 years. Probably the owner of this house use wrong product. As far as I know, penetrant sealers (siloxane) is less likely to have this problem (turning yellow. Anyway, thank you for your answer.