Can Dow Corning 791 be painted over?

[DIYNotIan]

Hi all

I'm planning on using this for sealing around some window frames.... Has a great rep.

But I'm hearing differing opinions as to whether it can be painted over or not...

Can anyone who has used please let me know.

Cheers

Max

 

[TheDec]

I take it you mean Dow Corning silicone, if so and you are intending to use a waterbased paint then it can be difficult and your paint can tend to ciss/separate, paint it first with a thinnd oil based undercoat prior to using a waterbased system and you should be ok.

Dec

 

[DIYNotIan]

Oooops! Post title amended!

I'd need to get an oil based U/C but that's fine. What/how would I thin it?

 

[TheDec]

Thin it around 5% with either white spirit or turpentine substitute.

Dec

 

[Mr Ed]

No, no, no! Never use silicone sealant anywhere where overpainting is required. Use a hybrid polymer such as Soudal Fix ALL Flexi. In fact, hybrid polymer sealants are now recognised as offering superior performance than pure silicone for most building work applications . . . with the major advantage that they can be painted over.

If you have silicone around window frames, for a quick fix apply a light coat of Soudal Fix ALL Flexi before attempting to paint, paying particular attention to bridge the join between the silicone and the frame. It bonds to silicone, and you will then have no problems with either water or oil based paint adhession. However, for the very best results, all old silicon should be removed and replaced with Soudal Fix ALL Flexi.

 

[opps]

I second the use of MS polymers but never apply oil based paints directly over them. The paint will never dry, or rather it will stay tacky for months (seriously).

Apply waterbased undercoat over it first and then apply the oil based paint.

FMS polymers do cost twice as much though but they have the added advantage of being able to stick to damp surfaces.

 

[conny]

Whenever I've used silicone around windows/skirting boards etc I have ensured the silicone is below the join then filled with painters caulk.
Never had any problems with paint finish afterwards.