The safest thing to do is to use waxed shellac over polyethylene so that you can decide on the lacquer without any worries.
Spraying paint on urethane would be no problem, no problem. Don’t cut the urethane, that would be the only problem. If you cut or slice it very finely, the strong paint thinner can penetrate and potentially lift the urethane.
Some types of paint are incompatible with certain paints. So, if you don’t know which paint and varnish are compatible (a question a good supplier can answer for you), the safe approach is to build a bridge between the two by placing a layer of shellac between varnish and varnish.
You should be able to spray paint over a 2K urethane primer. With PPG products, this is entirely possible. Inversion (2K urethane paint over lacquer primer) is not recommended.
In this case, polyurethane varnish over nitrocellulose varnish is generally harmless if the nitrocellulose varnish is old and there is no gas left.
Oil-based and water-based polyurethane can be applied with latex / acrylic paints, but oil-based polyurethane gives a yellow or amber color, especially on light colors. You can also purchase spray polyurethane, which makes it a little easier to apply, especially on larger projects.
Polyurethane is a more durable coating. If necessary, wash parts with naphtha and a reddish brown Scotchbrite ™ pad to remove oil or wax and rough surfaces. Apply a coat of waxed shellac or Zinsser SealCoat ™ and allow to dry overnight before starting the top coat.
Fir urethane is considered to be much easier to apply than polyurethane. It applies like polyurethane, but dries faster and doesn’t require many coats and applications to achieve a glossy finish.
Shellac has it all covered. When working in the opposite direction or when applying other finishing coats to shellac, it is often emphasized that polyurethane should not be applied to shellac. However, it is acceptable to use oil-based urethane in place of shellac.
1 answer. Paint can adhere to epoxy. In the worst case, the scratches on the epoxy surface under the finish coats are clearly visible, they are not wet from the finish coats, as would happen if the same paint had been applied.
It is recommended to seal the epoxy before painting. They said you can paint over epoxy, but the best result would be a sealant.
The paint is absorbed into the wood to create a better and more permanent bond. And this is one of the main characteristics that differentiate it from polyurethane, because the latter is more a layer for wood than a polymer. Lacquer is also one of the easiest wooden surfaces to apply.
Lacquer is the fastest way to dry wood furniture surfaces. It is stronger than shellac, although it is very thin and should be applied in several thin layers. It is available in glossy, semi-glossy and matte versions, in transparent form and in various transparent stain colors.
Re: Spray a new paint on the old paint
Apply 3 coats of polyurethane, especially if using an oil-based finish. The first layer must be mixed with white spirit. This acts as a sealant and creates a barrier between the wood and the oil treatment used. A brush is needed to apply the layers.
You read that right, the new paint can be applied over the old one without removing the old one. Thoroughly clean the surface, then sand just enough to completely remove the current shine. Clean with a rag, the rag.
A paint (or painted appearance) can be achieved with products or combinations of products that contain polyurethane, paint, epoxy resins, etc. Basically you can apply Danish oil paint or polyurethane. Just like you can with any drying oil. The key to success is to make sure the oil is completely dry first.
In most cases it is safe to apply paint to oiled wood, as the paint also contains oil. An exception to this rule are water-based paints. Find an oil-based paint and read the instructions on the package to make sure it is compatible with an oil finish.