Painting & Preparation

[Nathan Clark]

Quick question to all and I am sorry if this has been asked before, I'm just chasing some opinions on what sort of Preperation and what metal primers are recommended after the hull has been sandblasted. Do you need a particular type of metal primer for the bare metal, also I've heard something about washing the steel with a acid before the primer is applied. Any hints or tips when applying? Any help would be greatly appreciated.

[Private_collector]

Nathan,

I always prepare new or clean (as should be with blasting) metal with an etch primer. You should make your selection of etch based on compatability to your primer, and primer type to suit your finish or top coat.

You will notice I said clean should be the case with blasting! If it is you doing the work I would wager that you will probably take extra care, but professional blasters wont spend the same time to get it perfect. I bet you find a number of areas not quite so clean, usually in tight or out of the way places. It is difficult to get things 100% in a dusty blast helmet. Any spots that you suspect may still have any surface corrosion must either be treated with a rust neutraliser or removed entirely by mechanical means.

Most sandblasting companies apply a coat of etch primer once the blasting has been done. Be sure to enquire if the coating is standard primer or etch! It is widely believed that an approprite etch prime coat will give better adhesion to the bare metal. I even reapply a light coat of etch to any areas of bare metal after final sanding, just before top coat spraying starts.

Etch does not offer much in the way of filling, so several coats of primer (compatable with your type of top coat) is best after the etch. If you have areas of body filler or place where heavy filling is desired, spray putty is the product you will need. As always, spray putty MUST be compatable with your other paint layers.

The following is my process:

Bare metal - etch primer.
Rust scale or flakes - must be entirely removed.
Surface staining or light rust on surface - rust neutraliser or mechanical removal, then etch.

Primer surfacer - minimum of one coat if not sanding, or if you are going to do repairs to the area and will be taking that coat off for that. I do three good coats, followed by a mist of black, because when you sand you will know everything is flat when all the black dots are gone. I will always wet sand, but thats just my personal preference.

If repairs have left deep scratches or if body filler applied - 1 or 2 coats primer then several coats of spray putty. Can use a wiping putty instead of spray, if area is small enough. Apply the black (or other contrasting color) guide coat, as per primer. Once sanded flat, return to the primer step above, for that area. The other areas should have already been primed.

One of the most important things to be aware of is that no primers or puttys are waterproof. Neither are they intended to remain without top coat for an extended period. If you are planning to do heavy repair work, etch alone will be OK until then, provided the repair work involves sanding and re-etching etc.. Exactly how long is too long to wait with exposed etch, primer, or putty.........well thats a point of great debate, and will also depend on what conditions your vehicle is stored in.

Adhesion to any surface, bare metal or not, can be improved with light abrasion of the area. Emphasis on light, 180 to 240 grit sandpaper will be adequate. After blasting this will not be needed. The tiny pitting does that job!

Hope this helps. Excuse if I have written about steps you are already knowlegable about.

[Nathan Clark]

very good, you answered all my concerns. One last thing, do you have any recommendations on brands to use and ones to steer clear from?

[Private_collector]

Originally Posted by Nathan Clark

very good, you answered all my concerns. One last thing, do you have any recommendations on brands to use and ones to steer clear from?

Nathan,

Thats where I wont be of much help, Im afraid.

I was a spraypainter many years ago, but have only really had recent evperience with one type of paint, Protec Barrier, in a pre mixed color, camoflage green. It would not be an authentic color for your carrier.

Broadening back to Protec brand, I am impressed with the performance of this paint, or at least the "Barrier" variant. Well, take a look at post no. 96 on this page: http://www.mapleleafup.net/forums/sh...t=15575&page=4

I have used spies hecker and glasurit (? spelling) brands in the distant past. Both are two component paints (you add hardener) and are very good brands, but, and theres always a but, they are not easy to spray. So, I guess thats a long way of saying my experience is somewhat limited. Others may be able to offer greater insight to other brands.

Personally, I would only use a two pack type of paint, for its added durability, resistance to fuel and lubricants, and quick drying. I must add that other brand drying time may vary from my experience with the Barrier from Protec, though as a rule of thumb, any of the two pack paints will dry much quicker than enamels. I wouldnt even consider using acrylic paint. Not very durable, that stuff. Easily damaged and it 'sinks back', meaning as the solvents dry over a period of days to weeks, any surface imperfections will become more evident, even on flat paints.

Find a good and friendly local automotive paint shop, then tell them what you are restoring. When they know exactly what you need your paint to do (and look like) they will be your best source of information & advice. Never be afraid to ask questions, even of you think it may be a dumb question. It may be more important than you first think.

[RichardT10829]

As above for prep but paint wise I use cromadex paints and use their 222 fast air drying stuff I buy the thinners from them with the paint, they can colour match too... I use 10% matt finish they use all the BS codes and RAL codes too, it's a good hard wearing paint used by the British forces even now ! Two pack solids are getting harder to get here in the UK colours are limited.... As with all paints, but especially two pack make sure you wear a respirator up to the job, eye protection and coveralls ! That goes for your etch primers too.... Nasty stuff

[RichardT10829]

Also forgot to say if you go cellulose make sure you check it won't react with your primer.... You may need to put a stopper on top of the primer if you find it will react with your base coat. Also sorry about this...... Don't burn your money on high quality finish thinners for military vehicles.... Standard thinners will suffice ;-)

[Private_collector]

Richard speaks truth! This is one of those rare times when it's not important to buy the most expensive materials. Do get a high quality mask, and make sure you have a good in-line water trap on the air hose. If water comes through the line, you are basically blasting water into your finish. It will then reappear as raised spots, at some later date, and rust will start to form on the metal beneath.

Dont waste money on an expensive spray gun either. I use a SupaCheap Auto gravity feed gun that was less than $100, possibly much less, I dont remember. It serves me well, is very adjustable, and provided I clean it well after use, should see me through my restoration. If it does start yo play up, it will go into the bin, and I buy another one. Don't really think that will happen.