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paul connor

Spraying Olive Drab paint - hardener or no hardener

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Hi all, 

I always buy my paint from https://www.militaryvehiclepaint.co.uk as they always seem to get the shade I require, and paint can be very hit and miss to what you actually get , regardless of paint code.

 

My question is this, with an enamel paint, such as Olive Drab, do you personally add hardener or just spray as is? I have success with both, I was just curious if I should always be adding hardener to these products to create a tougher more durable finish?

 

Thank

 

Paul

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Hi Paul

First do you want the paint to last or do you want to repaint every 5 to 10 years?  The problem is the flattener used in OD is a porous matierial that lets water into the paint.  Hardner make the paint dry quicker, get hard quicker and hardner by itself tends to make the paint shinny thus figthing the flattener.

One approach that I have been using for nearly 40 years is as follows:

First color coat is NON flattened enamal of chosen color with hardner added. Gives good sealer coat and shinney finish.

Second color coat is where you add the flattener, the trick is to put the second coat on at the minimum time between coats this give a very good bond of the two layers.

Now having said this and gotten very good results on a number of trucks over the 40 years, I've also used very good paint mostly Dupont Centary.  I've gotten a very close match to the original colors on my CMP HUP, if anybody wants the Dupont paint mix numbers will be glad to share them.  One last point with this approach is that the color match is from one batch to another is very good, even with paint 5 years apart.

One of the advantages that I have noted with using this approach is that the paint jobs with hardened first layer seem to resists scratches from brush on trail rides.

Hope you will this information helpful

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OD paint is porous at the surface to give it a matt look. This property is because of the addition of a matting agent such as precipitated silica but only at a dosage of a few percent. Water will certainly not penetrate through the paint layer such that the metal underneath will rust because of the presence of the silica or matting agent. On the contrary, the presence of silica will have a positive effect on corrosion because of its anti corrosion property.

Weathering of coating films causes, in particular, a change of the film surface as function of time. Depending on weather conditions and on the resistance of the binders, pigments and fillers used and on the pigment volume concentration, there will be more or less degradation of the coating film surface. In the case of matted exterior coatings, the  choice of binders is quite important.

Cheers,

Danny

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Why don't you as the paint supplier for a  'Technical Data Sheet'  ,   reading between the lines you are intending to use a air drying enamel.  on the lines of a synthetic single-pack alkyd enamel.  This is a machinery / chassis enamel that is fuel & oil resistant when through dry.   A better quality would be a PU (polyurathane reinforced) often called a Fleet Enamel (used for cab livery).  IMHO - you would never use a hardener with these paints,  normally a maximum of 'matting-base' is  50%  (takes the place of varnish resins) , this will only get you to "Satin"  ,  a true matt (lusterless) - another kettle of fish.

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