Adhesion issue with paint

It takes two to tango. The base coating and the finish need to be considered. Silanes are generally added but the base coating has to be considered. If it contains any waxes or silicones (used for anti-blocking) then you will have a problem. Suggest you abrade the first coat - a very fine abrasive is adequate to take off the surface and provide a key. Other trick used is to soften the surface with a suitable solvent but the choice of this could require a paint chemist as to get the correct effect the balance of true solvent to diluent has to be found.

That's a question that would be best answered by the manufacturer of the product.

Each manufacturer has their own recipe and not all paints are created equal.

There should be contact information for the material purchased. If you're working for a company that uses this product that contact information could probably be found on the MSDS and you're supposed to have an MSDS for that product, it's OSHA requirement.

I assume that you are using a two component epoxy - mixing of hardener+base

a) Pl ensure that the two are from same company

b) the two are the recommended specifications

c) mixing is in proper proportions (in fact for best results some times, we weigh and mix)

d) ensure the mixing is thorough

e) the painting must be completed before the mixture sets in. there is a recommended time before which this total painting must be completed. the two components are more or less stable, till mixed. as soon as you mix these, the polymerisation sets in

f) The compatibility with the primer coat has to be ensured (in case of intermediate coat that too on both sides - ie primer to int and int to finish)

In brief follow strictly paint mfr guidelines, including recommended surface preparation, and start painting as fast as possible before oxides starts setting o to the metal (and it may start very fast).

Follow the recommended intercoat intervals (if you apply the coats before first coat is dried, the solvents of the primary coat may not have chance to escape.

We have a method of Process Qualification of painting (like any other special processes- like welding , Ind Hardening, Carburising, Nitriding etc) at our works and I recommend you qualify the process before starting the actual.

the hardener in the clear coat is most likely heating the clear coat to a higher temp than what you using. the addivitves I have used worked on their ability to heat the undercoat enough to achive adhesion.

What additives?? Additives are part of the original formula - any thing added to a coating will be more likely to cause problems. Leave the formulation to the formulators. In any case the heat dissipation from a thin film will be so high as to be of no consequence.

Most people I know add a hardener to their clear coat for a tougher skin.

Some people double up om the hardener with 2pack isocyanates to get a really hard coating suitable for anti graffiti work. But unless you have the skills be it on your own head.

The hardener is not an additive - it is part of the formula!

Paint companies spend millions working out coatings - find the correct coating - do not muck about with existing ones.

Over 90% of failures in painting can be attributed to application faults.

We take a pint of Activator for a 2 part epoxy and add it to a quart clear coat paint. It hardens the clear coat for much tougher skin. Of course we have been paint things like dump trucks and work trucks for year we might not have any idea what works after all.

Which activator ?? which epoxy ?? There are always those who know better than the original maker and only read the label when all else fails. If it works for you then you are lucky - after 60 years in the coatings industry I still find that 90% of failures are due to application problems. That does not mean that all paint jobs perform as can be expected and guarantees are like hens teeth.

You are probably over-spec for the job. Construction equipment gets rough treatment and does not have to last long - if it works for you keep it up otherwise please not infer that it is OK to do your own thing. You are lucky!

We just use the cheapest clear activator we can buy usually about $2.00 a pint at the auto paint store. We live in the country and car out here travel gravel roads for the most part and get rubbed by tree branches on drive ways or brairs along fences.

What we do helps fight off the scratches and dings mostly.

The paint used is a 2k polyurethene.Added to that is a mix of 2 different solvents and a catalyst.

An adhesion promoter is then added to that mixture.

The mixture is used in airbrushing a graphic onto a painted and cleared surface. When the surrounding mask of the graphic is pulled, the airbrush is peeling along with it. Wait time seems to be somewhat of a factor, but the airbrush area doesn't seem to be curing fully.

The solvents used in 2K products are very strong and can act as a paint remover and soften the coating below it. In some cases this is an advantage as this can virtually weld the two together. Once the system skins over, trapped solvent can give you adhesion problems but if allowed to come out it can be OK. Solvents can be trapped in coatings for years as they are released on a half-life basis so in actuality there will all ways be some there

Try 1. Let the graphic dry for longer preferably in a warm situation and see if it will harden more. If it does not wrinkle or craze after putting on the 2K then let it dry for longer again a warm (not hot - +- 70ºC) environment. Solvent may be retained by the graphic and so soften it. Infra red lamps can help a lot.

Try 2 Using the 2K in colour for the airbrushing - they are virtually available in any colour for auto respray.

Remember when spraying 2K that you are dealing with isocyanates and this can have bad effects on any one & especially those with an asthmatic condition. Air fed respirators are generally advised.

You would probably do just as well with a good 4-hr industrial enamel. You are not on an oil rig or in a chemical environment. But if it works for you then OK obviously a non-critical environment.

In general mixing things into paint can cause problems and as the cost of repairing the surface for re-coating can be prohibitive

You guys have given me food for thought and possible avenues to go down in trial and error city. Much appreciated

A painted surface where you are going to be adding another coat of paint needs to be scuffed up a little. Especially if the existing surface is a glossy coat and is dry.

A regular brillo pad is enough to scuff the surface for the new coat of paint to adhere too.

The scuffing does work, but according to the paint manufacturer with the adhesion promoter mixed into the paint, the scuffing isn't needed.

We change our paint brands all the time trying to save a dollar or trying to find something that will stick to our machines better.

We have paint companies all the time coming to us to try their brands because we do use a lot of paint.

We use an epoxy mix.

Some of these samples we tryout we paint on the metal and next day it peels off like peeling a banana. The salesman always accuses us of not doing it right or the conditions weren't right. We can't wait for the conditions to be perfect for the paint, we need to use the paint right now.

The manufacturer says you don't need to scuff the surface, which is commonly called prepping the surface, I call bunk. I do because they are selling you a product and they want to give you the impression that their product is easier to handle then the competition and they don't want you to take your business elsewhere.

Because that is my line of thinking, I'd prep the surface all the same because I don't exacly trust everything that someone trying to sell me a product is telling me because I just feel I'm getting an overinflated explanation on the paints actual performance.

It's embarrassing to have to go back to a customer where we've installed a line of machinery and have to repaint everything shortly after completing the installation.

Change your manufacturer. Her cannot know the condition of the surface - unless he has a Crystal ball or personally inspects it.

All old surfaces should be cleaned and scuffed before re-coating!

Adhesion promoters especially those used for glass fire (silanes) are best used in the surface which is to be coated rather than in the coating. Sounds like another merchandising ploy.