Rust and Lead Encapsulation

[daviv]

We have a project where the contractor is required to remove loose paint which structures which contain lead paint that have rusted over the years. Afterwards, they are required to apply 1) Rust Primer (to control the rust), 2) Another Primer coat (to encapsulate the lead paint), and 3) Final coat. These 3 layers are part of the manufacturer's system to control the rust and lead paint. However, the contractor applied only 3 layers of final coat. Currently, we are seeing some rust on the paint. The contractor has proposed applying 1) Rust primer and 2) final coat. We want them to remove the coatings they have applied and apply the coating per contract. Our proposal is certainly more expensive. My question is would the rust primer work if it is not applied to the rust itself? Would the rust bleed through if the rust primer is applied to the final coat? And any suggestions for a work around?

 

[TugboatEng]

What is rust primer? If it's a chemical conversion process like phosphoric acid, then no it won't do anything if applied to paint. What level of prep was done? If you apply any coating over rust scale it will fail. What is the top coat? If it's a surface tolerant epoxy it will likely perform as well as the primer. If it's a polyurethane top coat it will likely not have the film thickness to property protect against corrosion.

 

[daviv]

I do not know what a chemical conversion process is but the rust primer is a water-based acrylic. Only loose paint were removed. The top coat is also acrylic. By the water, are we allow to mentioned the manufacturer in the post?

 

[GGedge]

Any rust staining showing through the applied paint is caused by corrosion of the steel substrate under the applied paint. Putting more paint on top of what is already there is not going to stop that corrosion but might hide the staining for some time.

Whether making them apply as per contract will stop the problem is debatable given the specified surface preparation, it is the preparation that determines the performance of the paint applied to that surface.

 

[TugboatEng]

If mentioning a manufacturer, I say go for it if it contributes to the conversation. An example would be allowing us to see data sheets to evaluate the methods of preparation and suitability of the paint for the application. If it's a hit against the manufacturer, claiming their product has failed, then I would say that it would be inappropriate to post their information in this case.

With that out there, I have zero experience with water based acrylic paints on metal.

 

[daviv]

The manufacturer is Global Encasement. We are considering several options. 1 option is to have the contractor remove the coating they applied which would also include the existing lead. This would most likely lead us to make a claim on the surety. 2 option is a suggestion made by Global Encasement which they consider the next best option. The contractor would add a coat of rust primer and final coat to what has already been applied. However,Global Encasement would not warrant the product. What you guys go for this option we can negotiate a settlement for possible future maintenance? Also, I am asking about a 3 option. Can you suggest a miracle product out there that would prevent the rust and encapsulate the lead paint?