Newbie question. Seam sealant?

[normal rules]

What is is, when do you use it and how do you apply it.

Any photos would be helpful .

[Ant-t]

Have a read of the thread I started below...

[normal rules]

I read the thread which prompted my questions. People on there obviously know the subject matter . I dont

[boatbuilder]

Seam sealer is rubbery stuff that you put on to seal up places where metal panels are joined together to stop water getting in and starting rust.
You can get two main types. One usually comes in a metal tube the same size as a normal tube of silicone. It's also known as PU or polyurethane sealant. You use a silicone gun to apply it and smooth it out with a suitable tool( i.e. gloved finger, lollypop stick). If doing a seam it's a good idea to put masking tape on both sides to keep it neat. Reputable brands are sikaflex and tigerseal although there are others too. This can also be used as a glue for example to glue a fibreglass high top to the metal roof.

The second type of seam sealer is brushable seam sealer that comes usually in a 1 litre tin. Goes on with a paintbrush that has had the bristles cut to about half normal length. Can be difficult to get it to go on smoothly. Best really for hidden areas like seams under wheel arches etc. Can be useful to smooth it out using a cloth on your gloved finger dipped in some panel wipe.

If you look at the end of my 84 Rusty project thread, there are some photos of some seams on the outside of the van I did last week with PU seam sealer.

The seam sealer that was applied in the factory in the 80s is usually cracking up at this stage and letting in water. Also Vw didn't seal the back of the seams inside the van so rust tends to start on he inside and work its way out through the seam sealer. Only solution is to either replace entire panels or rake out all the old sealant, remove and treat for rust, then repaint and re-seamseal it.

[bmouthboyo]

Sorry to dig this up but seems silly creating a new thread.

I had my lower panels replaced, sealed and painted about 7 years back but am not getting some seem rash again. I know in the long run I need to replace panel and get to all the rust but for the cost and my use I am looking at how to get the seem rash out, and minimise its spread / appearance.

What is the least invasive method in terms of disrupting surrounding paint which is OK?

I was thinking rake out old sealant (possibly with wire wheel but worried about damage to surrounding paint), mask up, treat with something (vactan?) then reseal (tigerseal?).Can I leave this sealant exposed of does it need painting over?

Thanks

[trentjim]

a thin blade craft knife/scalpel/craft knife

once the sealer is out and the blade is dull it can scrape deep into the seam, you will feel each spot weld so rub up and down each section between them - where the rust widens out of the seam target it with a dremmel - the wire wheels dont last long but if you find a good source of sturdy steel wire wheels for the dremel they'd be ideal - I often worked with a small pointy abrasive stone and a steady hand to grind the worst off and flatten it - not too much shiny metal showing, the vactan needs something to chew on
Then a tiny artists brush to get vactan right to the back of the seam.


 

[bmouthboyo]

a thin blade craft knife/scalpel/craft knife

once the sealer is out and the blade is dull it can scrape deep into the seam, you will feel each spot weld so rub up and down each section between them - where the rust widens out of the seam target it with a dremmel - the wire wheels dont last long but if you find a good source of sturdy steel wire wheels for the dremel they'd be ideal - I often worked with a small pointy abrasive stone and a steady hand to grind the worst off and flatten it - not too much shiny metal showing, the vactan needs something to chew on
Then a tiny artists brush to get vactan right to the back of the seam.

Thanks for that Jim. I assume sikkaflex so seam seal? And do you need to paint over or can you leave the sealant exposed?