If you haven't ordered the HDU, don't. Go get yourself .75" or 1" thick PVC for EXTERIOR use. You can probably get away with interior PVC considering your signs are going to be pretty small, but why risk it? Why do I say PVC over HDU? It's cheaper. It has a hard, smooth surface which is easier to get a high gloss finish, if that's what you want. It's more durable. In general, it's a bit easier to work with.
Second, paint doesn't just peel off unless it's done incorrectly. I've done things where paint peeled off. Why? Because I did something wrong. There are a few tricks that apply to painting, that really apply to dimensional work. The first is make sure your prep work is right. PVC is pretty easy. Sand it down with 180-220 grit. Clean it well. Lay down base coat. No primer needed. HDU is a bit more tricky. A lot of people take a garden hose and wash it off first. Then fill. Then prime. Then sand. Then potentially prime again. It depends on the finish you desire. Higher density HDU will require less work but costs a lot more. The second is let everything really dry. Most paints say you can recoat in 3-6 hours with latex paints. I wait 24 hours or more after my first coat. My second and third coats I'll do closer to the 6 hours but I'll often wait a little more. Often it's a coat when I walk in the door and one when I leave. The paint isn't going to absorb into the PVC or HDU like it will with wood. It needs to dry longer as a result.
The thing you will learn quickly doing this kind of work is you need your paints all to work together with your products. For example, if you put down a base coat of exterior Home Depot paint and then go apply your vinyl mask, it may or may not work. Why? Because if the exterior grade HD paint has various additives, it may cause the vinyl masking not to stick. When that happens, you're stuck hand painting everything which sucks if you aren't good at it. I'm fairly new at dimensional signs and I learn something new nearly every project, especially when using a different product.
For example, you couldn't pay me to use Modern Masters Gold on a v-carve sign. I read about it being a good product and many people recommend it but I would never think about using it again. You may use it and think it's great. It's a learning experience. One last thing, I only skimmed this thread for other people's responses, but in general, you're going to get a lot of mixed advice. For example, I read one or two things that are flat out wrong. You're going to have to do your research and some testing to find what works for you and what's the truth.
Sorry, one last thing. You can't call many of the companies and get good advice. I've called them all. Komacel, Duna, Precision Board, SignFoam, ect ect ect. They all had little to no advice on paint compatibility. Their stock answer is any paint will work with their product as long as you prep the material properly. What they say isn't false but it isn't entirely true either.
Second, paint doesn't just peel off unless it's done incorrectly. I've done things where paint peeled off. Why? Because I did something wrong. There are a few tricks that apply to painting, that really apply to dimensional work. The first is make sure your prep work is right. PVC is pretty easy. Sand it down with 180-220 grit. Clean it well. Lay down base coat. No primer needed. HDU is a bit more tricky. A lot of people take a garden hose and wash it off first. Then fill. Then prime. Then sand. Then potentially prime again. It depends on the finish you desire. Higher density HDU will require less work but costs a lot more. The second is let everything really dry. Most paints say you can recoat in 3-6 hours with latex paints. I wait 24 hours or more after my first coat. My second and third coats I'll do closer to the 6 hours but I'll often wait a little more. Often it's a coat when I walk in the door and one when I leave. The paint isn't going to absorb into the PVC or HDU like it will with wood. It needs to dry longer as a result.
The thing you will learn quickly doing this kind of work is you need your paints all to work together with your products. For example, if you put down a base coat of exterior Home Depot paint and then go apply your vinyl mask, it may or may not work. Why? Because if the exterior grade HD paint has various additives, it may cause the vinyl masking not to stick. When that happens, you're stuck hand painting everything which sucks if you aren't good at it. I'm fairly new at dimensional signs and I learn something new nearly every project, especially when using a different product.
For example, you couldn't pay me to use Modern Masters Gold on a v-carve sign. I read about it being a good product and many people recommend it but I would never think about using it again. You may use it and think it's great. It's a learning experience. One last thing, I only skimmed this thread for other people's responses, but in general, you're going to get a lot of mixed advice. For example, I read one or two things that are flat out wrong. You're going to have to do your research and some testing to find what works for you and what's the truth.
Sorry, one last thing. You can't call many of the companies and get good advice. I've called them all. Komacel, Duna, Precision Board, SignFoam, ect ect ect. They all had little to no advice on paint compatibility. Their stock answer is any paint will work with their product as long as you prep the material properly. What they say isn't false but it isn't entirely true either.
