How To Protect Metal Before And After Welding?

[mattw 2]

I've done a search but found nothing.

 

Basically once the rust has been cut out and a new section of metal welded in, how do you rust proof/paint the underneath of the repaired section??

 

For example, if there was rust at the bottom of the windscreen which was repaired, how can you get behind the repair?? May apply to sills etc as well?

 

May be a silly question but just curious!

 

Another question....once rusty metal has been removed and cut out, is there a primier which can be applied for the time between cutting and welding (eg could I cut out rust, prime the area and weld it up later?)

[welshpug 1,621]

weld through primer

[mattw 2]

weld through primer

 

Will that last for a while?

 

Any ideas on how to protect behind the weld??

[DamirGTI 323]

Depends on if you can reach the back side of the welded area or not if you can , use good quality zinc or red oxide primer , if you can't you'll need air compressor and a few spray gun attachments ..

 

When ever theres a hollow section on a car , like for instance sill , and you need to weld a repair patch somewhere at the middle you can protect the inside area of the patch with the wax oil gun trough the holes on the sill (theres 4 of them if i'm not mistaken .. or 3 i can't remember ..) , for this job i have two UBC shutz/wax oil guns with long PVC hose attachment (for deeper access in closed/hollow body sections) i use one of those for spraying usual stone chip coating/wax oil products and another one for spraying paint (zinc rich or red oxide primer , or rust inhibitor/converter) i just clean up one used UBC wax oil bottle , fill it up with paint , screw the bottle on the gun , add pipe extension attachment search for a hole in the bodywork section (theres always one !) so that i can reach the back side of the welded part and stuff the pipe inside as far as it goes and spray the hell out of the insides afterwards , after a few hours when the paint/primer should be well dry , i go over once again but this time with wax oil .. and that's it

 

Damir

Edited November 27, 2009 by DamirGTI

[mattw 2]

Depends on if you can reach the back side of the welded area or not if you can , use good quality zinc or red oxide primer , if you can't you'll need air compressor and a few spray gun attachments ..

 

When ever theres a hollow section on a car , like for instance sill , and you need to weld a repair patch somewhere at the middle you can protect the inside area of the patch with the wax oil gun trough the holes on the sill (theres 4 of them if i'm not mistaken .. or 3 i can't remember ..) , for this job i have two UBC shutz/wax oil guns with long PVC hose attachment (for deeper access in closed/hollow body sections) i use one of those for spraying usual stone chip coating/wax oil products and another one for spraying paint (zinc rich or red oxide primer , or rust inhibitor/converter) i just clean up one used UBC wax oil bottle , fill it up with paint , screw the bottle on the gun , add pipe extension attachment search for a hole in the bodywork section (theres always one !) so that i can reach the back side of the welded part and stuff the pipe inside as far as it goes and spray the hell out of the insides afterwards , after a few hours when the paint/primer should be well dry , i go over once again but this time with wax oil .. and that's it

 

Damir

 

I guess you can't then be 100% sure its covered then if you cant see it (but I assume if you spray enough it will cover it!!)

 

Just thinking about all the possible things that could mean rust comes back.....no one wants to do rust repair again!!

 

Do you have links to where i could get hold of the attachments you mentioned above??

[boombang 2]

Bilt Hamber etch weld through is the only weld through primer I'd use.

 

You can genuinely weld through it, and adhesion is miles above others I've used.

 

In fact, if I started my automotive life all over, I'd have bought a hell of a lot more stuff from them.

[DamirGTI 323]

I guess you can't then be 100% sure its covered then if you cant see it (but I assume if you spray enough it will cover it!!)

 

True , but what i usually do is make a template (a "dummy" box section..) of the closed section (similar to the one on the bodywork) from cardboard and then try a few time test/trial spraying the insides until i'm 100% sure that the pressure settings is spot on , gun/hose movement etc. and so is the covering of all the inside areas ..

 

Anyway , the nozzle on the end of the PVC gun hose has holes at an angle (3 or more holes) so when you stuff the hose inside the closed section it'll spray the product in three (or more..) different sides , like sideways left<->right and top to the bottom as well

 

.. something like this will do :

 

 

.. though you can get one with even longer hose (or you can stretch the hose easily by adding longer one ..) and spec. gun with container for spraying rustproofing fluids , like this :

 

http://forum.ih8mud.com/attachment.php?att...mp;d=1227303673

 

Damir

[SurGie 54]

Iv always thought about how to go about this problem properly.

 

What if, like the sill for instance has an inner surface rust area that the zinc primer dont stick well enough to ?

 

Would it be an idea to also spray rust treatment within the sill, after it has dried out then spray within the sill

with the etch primer ?

 

Also if you use weld through primer, wont the primer burn away around the weld line area, then start rusting ?

[CosKev 16]

I've used Dinitrol Cavity wax in all box sections etc:

 

http://www.rust.co.uk/popup.cfm?p_i=405069&p_n=405069

 

Highly recommend it,alot thinner than wax oil so gets everywhere in all the seams etc

 

After spraying the inside of my rear quarters and pillar area this appeared:

 

 

Goes to show why 309's rot like hell on this seam

Edited November 28, 2009 by CosKev

[Pug_101 0]

This has to be one of the easyist ways to get in behind areas in a cavity.

The tube is really small.

 

Bilt Hamber

 

My new 205 is likely to be 95% Bilt Hamber by the time i've finished it

[dee205 3]

Know a few guys who've used Bilt Hammer and they say it's the business. As above too, mine will be 95% bilt hammer by the time it sees road again.