Sikaflex 221 vs 512 (1 Viewer)

[veevee]

We have much easier access locally to Sika 221 than 512. Can pick it up locally easily and good stocks are kept too.

I have to make an urgent repair to something and having used Sika 512 a couple of times was happy to us that, but it will create a 3-5 day delay. On the other hand it's possible to buy 221 locally tomorrow morning.

Looked up the DataSheets for both and they are similar but not the same. Has anyone used both of these to have an opinion?

BTW, have to seal galvanised sheets where the supports have moved and gaps have appeared.

 

[Minxy]

I have used Sikaflex 221 to fit my flexible solar panel without a problem, data sheets here:

 

[Gorse Hill]

You can get a galv sealant/adhesive which is designed for the job, not sure about the specc on either sikaflex you quoted if they have approval for this application, although I accept sikaflex is top draw

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[DBK]

The available information is a bit sparse but if I had to guess I think 512 is more elastic and therefore more suitable for joints with a bit a movement. One clue is 221 is described as suitable for being sanded and painted which I don't think you could do with 512 based on my limited experience using it to stick a solar panel.

So which to use? For a body joint in a MH then 512, for something small on a MH then 221.

 

[Badknee]

512 is the one to use in lower temps otherwise 221 is fine.

 

[Gorse Hill]

512 is the one to use in lower temps otherwise 221 is fine.

Does it have approval for use with Galv?

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[TheBig1]

I have used it to rebond galvanised steel ribs to the outer skin of a panel van with good effect. the reason being to reduce body noise they are normally bonded with a similar urethane based sealant glue, but some on that van were missed in manufacture. was still quiet a couple of years later, so apparently retained full adhesion
as said 221 is less flexible than 512 and is stable enough to over paint without the paint cracking due to flexing

 

[musson]

I used 512 on solar panel and sat dish mounts spoke to supplier,it was what he recommended