Help with vactan

[orangebooboobearcrew]

Hello,

Sorry, this is my usual type of silly question but please bear with me...

I have been using vactan rust inhibitor for a couple of years now following the various recommendations of others on here.

However, every time I have used it, (I have always brushed on with 1 inch brush), I seem to get brush marks and even when flatting back with 800 or 1500 wet and dry, either go through the layer just put on or still have brush marks which show through on the final coat.

What am I doing wrong?

Should I be using high build filler primer which would fill the brush marks before topcoat? Presume normal basic grey primer no good here...? Or is the issue how I am applying the vactan?

Cheers,

Chris

[kevtherev]

I find brush quality affects the application, and I always cross hatch the coat just before it goes off.
My father painted coaches with his trusty fine sable brush and cross hatched his coats till they were without marks.

[jamesc76]

Or is the issue how I am applying the vactan?

Cheers,

Chris

I'd go for that bit! even with manky old brushes I can get a smooth finish with most paints!

[orangebooboobearcrew]

Ok, thanks both.

Kev, I will try the crosshatching and see if that works.

James, would you have any suggestions then as to technique?

Thanks,

Chris

[Roving Rich]

Glad you asked that, I have exactly the same problem.
Seems pointless putting on a rust proofer, seing it all turn black, then sanding it off and getting it wet !
I've done all my seams with it, but now need to apply some rustoleum paint.
I tried "crosshatching" or "laying off" as my sign writer friend calls it, but it still has brush strokes in the vactan. Looks a right mess now.

Cheers
Rich

[orangebooboobearcrew]

Yep - I agree. Even with cross hatching, whilst better, still shows up under paint with brush marks.

Anyone got any other solutions?

Also, I presume you only use vactan for small patches - you wouldn't use for a whole panel for example? What would you use if you take down to bare metal - just zinc primer? Would that be waterproof?

[boatbuilder]

This is one of the reasons why I don't use vactan much.
I prefer to treat with phosphoric acid, rinse it off with water, dry it well with a heat gun and then apply zinc rich epoxy primer right on the metal.

[CovKid]

Sounds you me like you're putting far too much on. You only need a thin film of Vactan, Really squeeze your brush out before applying.

[bootie3367]

I have never used Vactan, but plenty of other rust 'converter' products.

using one out here on the rig at the moment, it's a generic converter, milky white in appearance then goes black.

Here's the thing, once your rusty surface goes black then the converter has done it's work on a molecular level, binding with the rust to form a waterproof and solid layer. At that time, (in our case approx 30 mins) it should be washed off with clean water and left to dry or artificially dried.
If you have brush marks then it has layered too thick and in all probability may peel at a later stage. It is only supposed to be a number of microns thick, (can't remember the figure we have) so of course you will have to spray a filler primer as the metal you have treated will not be smooth due to the pits from the removed rust. That's the reason you use vactan or similar, to make sure the rust left in the pits is converted, otherwise, as you all know, it comes back with a vengeance!

Sorry if this seems to be teaching grandma to suck eggs but from what I could see on previous posts you seem to be missing the point of the converter.... it's not paint! It won't work properly if too thick, well it will but you must get rid of the excess.

I would never put vactan on bare metal, why, it's bare metal, rust free!

Coat on and

[orangebooboobearcrew]

Both,

Thanks for your input - some good advice there from both of you.

More than happy to be taught 'how to suck eggs'; that's why is asked cos I don't know the answer

I will try both putting a lot less on by wiping the brush and then use filler primer to fill anything left behind.

Will let you know how I get on...

[CovKid]

I mentioned this in another thread recently but theres a natural inclination to put more on with the assumption its doing more good but it doesn't work like that. Bootle3367 is spot on, with 40 microns about right, merely a trace. Because Vactan is carried within an acrylic binder it can have a rubbery consistency if piled on which makes it very difficult to sand. Stick with a very thin coat - enough to follow the contours of the rusty surface and no more. Any levelling is down to filler primer. In fact a very fine brush is best in seams and definately not a 1/2" paintbrush or similar. This is why the smallest bottle of Vactan is all thats needed.

[orangebooboobearcrew]

Thanks Covkid.

Yes, I think the size of brush is where I am going wrong then by the sounds of this - I have been using a 1/2" brush. I have got a little artists / modelling brush somewhere so will try with that and see how we go... I will get there eventually...

[orangebooboobearcrew]

used the artist brush yesterday and much better. Sprayed with filler primer and you can't see brush marks now so result I reckon!...

[CovKid]

As with all rust, you have to accept that in some instances it may simply ,come back. Often the only solution then is to cut out and replace with new metal (not fun on seams). If theres a small pinhole through to the other side and its in a spot where you can't see or treat the back, it will bubble up again. You have to assess corrosion carefully. That said most areas I reasoned could be halted with Vactan were stopped in their tracks but you do have to use it spraringly and with a very light touch. Its only there to stabilise the corrosion, the subsequent layers of paint do the actual levelling and sealing. Glad you resolved the prob.

[orangebooboobearcrew]

Cheers covkid and others.

Yeah, got filler and zinc primer on now and got a nice smooths surface ready for painting (I ordered the rustoleum dvd over the weekend).

Van looks much better just in the primer - looked like it had been in a drive by shooting before!

Can't wait to get painting...