21 replies to this topic

[mini93]

Howdy!

 

So, Im cracking on with the project mini currently.

I had the shell shot blasted a while back, when it returned I was given the advice fromt he blaster to throw primer at it straight away. I went against his advice as the clean-just-blasted steel was much easier for me to weld and carry out repairs on.

 

Now year or 2 down the line, surface rust has set in and I'm almost at the point in time where I'd like to get it to paint on the shell.

 

I had the idea from an early stage that It would just be easy for me to get the shell re-blasted before I head off to paint as it was a reasonable cost, this would then be suitable for the paint shop.

However, upon doing more work to the shell I'm apprehensive, I dont really want to risk getting any damage on the new fixed panels ahead of going to the body shop which could potentially cost me money to put right, having blast media lodged in box sections etc I dont really want to try fish it out. and where I'm sikaflexing aluminium panels into the shell I dont really want to damage these seals. so, I will avoid this all if possible by not going to the blasters.

 

Just to give an idea of what im up against here.

 

 

It really is just scale, its been in the dry relitivly warm garage, sections close to where I have welded have oxidised more sevearly than just bare metal sections

 

So, question being, what can I do to avoid going back to the blasters?

I dont have access to air tools or any specialist stuff, but suggestions welcome incase I can arrange something along the line.

 

And just to check here, what order to people apply seam sealer? I'll be using Sikaflex 221, flexable sealant, obviously this isnt silicone based. I have seen some people say sealant>primer>paint, whilst others say to prime>sealer>paint.

 

Thanks for the help,

Dave

 

[rally515]

Wouldn't the best method to Chemical ? Along the lines of K-rust, do that on each panel, one at a time over a certain period thats ok for you and then prime and paint each panel as you go.

 

That way it gives you painting practice and doesn't break the bank and leave you without much more money to do other stuff on the car.

 

Not sure if i'm speaking rubbish, but blasting thins the metal right ? so probably best to avoid the shock force process and aim for a chemical treatment.

Not the expensive acid dip the aye   ££££££££££.

 

 

Cliff

[mini93]

Blasting is very dependant on the blaster and the media used. He would only need to use very fine, soft media to remove the scale on the panels.

I have heard of K-rust before, but I dont know how it works, if anyone could explain, would be spiffing! then I could gauge if it'll be suitable

[rally515]

Oh if you're looking for an explanation, you've lost it with me  .

 

There is a few different brands and types on the market to be honest, I just mentioned that one as an example.

 

I know there are some that "Claim" to "Convert" rust but i don't like the thought of that myself.

The one id personal go for if i had the money would to Deox Gel by Bill Hamber.

That you apply, wrap in cling film and leave for a day or so and it makes sure work of getting it even pitted carbonised rust spots to lift it and require cleaning off and prime/paint.

But at the end of the day it all comes down to budgets.

[mini93]

Will, give it a budget. Less than £200 as thats what blasting is likely to be around.

I've been having a google to see what k-rust turns up... after finding out about some rapper, I stumbled across a few explanations. It turns out a few folk on here have asked perviously as it was just a few pages down on the results.

So... its not expensive, I think I'll pop over to Halfords tomorrow and pick up a pot, I've to clean some metal prior to painting and throwing in some more aluminium. previously I just used elbow grease and some 60 grit and I can imagine I will get tired of that sharpish!

If it turns out successful I can see how it pans out on a larger area and go from there.

[olly33]

I have being using kurust from halfords.My rust was more serious tho, so I had to sand down the bubbling rust to the pitted metal, then applied kurust.

It does say to rub the rust down, first.

Beware tho, a small amount goes far, its really runny stuff, and the rust will start to turn blue to black, apparently reversing the process.

 

I have also used deox gel, same again, rubbed down applied the gel, you can wrap in cling film if leaving overnight, otherwise leave for hour or so, then rub down while gel is still intact with scotch pad, and then rinse with water.Really great stuff, and biodegradable, no harmful chemicals in it.

[KaneH]

+1 on bilt hamber products, I've used deox gel and deox-c powder and both produce great results. For surface rust, like you have, you probably only need to leave the deox gel on for a couple of hours then go at it with a stiff brush and wash off. You may need a few bottles to do that large an area but they are not too expensive to buy so shouldn't be an issue.

Alternatively you could purchase clean and strip disks, basically nylon strands set in a resin which are formed into grinder disks. These will strip paint, rust etc without taking any metal away or generating any heat.

Stay clear of 'rust convertors', these are just a preventative measure which will only slow down the development of rust under your freshly painted panels not completely remove it.

Another alternative would be to have the shell soda blasted. Soda is a non-aggressive blasting media so will have no effect on the base metal itself, it should only remove surface rust etc. It is also soluble so can be cleaned of easy enough although proper care should be taken to ensure any moisture left behind after rinsing is removed.

[Morry Stu]

You can chemically treat it with rust convertor. This converts the rust from iron oxide to iron phosphate This actually forms a protective layer over the metal and gives an excellent base for primer.

It works very very well. All you do is pray it on making sure you thourughly wet all the metal and let it sit, usually overnight. You will notice the metal change coliur and will form a dusty white powder. Just rub this off with a green scotchbrite pot scourer and then blow with compressed air.

Rust convertor is Phosporic Acid.

Prob goes under a number of different brand names. It is also used as a food grade sanitiser.

http://en.m.wikipedi...Phosphoric_acid

[Morry Stu]

Stay clear of 'rust convertors', these are just a preventative measure which will only slow down the development of rust under your freshly painted panels not completely remove

This is not true. Rust converter like "Phosphoric Acid" actually converts the rust chemically. Its best used imediatly before priming. Its no good if you uses it and leave the metal to sit for another 12mnths. This goes the same for soda blasting etc.

[minivan1976]

if its light surface rust it should be removable by sand paper a 120 as a start then reduce the grade to a finer finish like 240 then 320 (higher the number the finer the paper) you can do this by hand if you dont have access to an air sander or if it's going to a paint shop they should be able to deal with that.

If its eaten into the metal a fair way then sanding and applying the rust converter should do the trick.

 

Hope this helps a little

[KaneH]

You have no guarantee that all rust particles found on the offending area will have been converted by the chemical solution. Yes there is the apparent change in colour once the chemical has taken effect although this can occur on the outermost layers of rust leaving untreated area laying underneath. If it were me I'd be looking to remove all traces of rust completely giving you the assurance that any your freshly refurbished car will last a lot longer.

I 100% agree with the comment of painting immediately after treating the area in question. I would clean back the panel with either of the methods described, blow off any dust particles and give a thorough wipe over with 'tac-rags'. This should remove any debris from the surface of the panel left behind from the stripping process and paint immediately.

Seam sealer can be applied over initial coat of paint and this is recommended as if you were to apply seam sealer on bare metal then you'd be having to wait until it had set (usually 24hrs) before applying your initial layer of primer therefore leaving your metal exposed.

[mini93]

Cheers for the info folk.

One thing that has me thinking though, that Deox-gel, it says to rinse with water... this just seems a little against my common sense!

I think I might get over to halfords/generic other store, see what they have kicking about, couple that with the nylon pad things.

I shall report back laters.

[sonikk4]

To add another fly into the ointment here is now every seam will have been open to the elements. Yes I understand they are not fully exposed but as the majority of mini rust starts within the seams they will be the worst place to remove any lingering rust.

To really get rid of this rust would be to chemically dip the shell.

[KaneH]

Chemical dip with an electro-coating would be the best option by far but the cost of the process is rather high.

The use of water is perfectly fine as long as the moisture is cleaned up/dried afterwards. When I've used it before I have removed all gel/debris with a rag, wash clean with water and clean rags, pat dry and to be sure that all moisture is gone I go over the panel with a heat gun. Apply prime etc etc.

[Daz1968]

Citric acid is a method I have read about, never tried it myself though,