Need Help Painting HDU foam...

[okeesignguy]

we are routing a sign from 1" thick HDU...
We have never yet done that...lookin for tips please....
What kind of paint or stain is best etc...?

Thank you!

 

[bellateres]

we are routing a sign from 1" thick HDU...
We have never yet done that...lookin for tips please....
What kind of paint or stain is best etc...?

Very important - First and second coats should be high quality interior/exterior latex primer.The primer coats will form the foundation and determine the quality of your finished product. Then sand, use tack cloth to remove fine dust. Next paint 2-3 coats, allowing adequate drying time between coats. We prefer high quality latex, drys quickly, easy cleanup.

We do not recommend paint with built in primer.

 

[okeesignguy]

Inside the relief is a wood grain look so sanding that would be difficult...
I assume by sanding you mean to sand lightly to dull the finish...?

Do you prefer any particular brand?

 

[bellateres]

Didn't know about the wood grain effect, so maybe one coat of primer.

The sanding applies to flat surface HDU panels which provides an even finish for the finish coats of paint. Sherwin-Williams and Benjamin Moore latex were our favorite brands.

 

[rossmosh]

The number one thing to remember about painting HDU/PVC is dry time and prep work.

If the can says dry for 6 hours, triple it. HDU and PVC do not absorb moisture. So all of the drying goes one direction. When you paint a wall or wood, it will absorb some of the moisture which makes the drying go much faster. So don't rush the paint.

HDU is also a material that needs to be really clean before painting. Sand it down to form a texture, blow it off, and then if you can, spray it with a garden hose. You want to get it clean as you can.

After that, it depends on what you're doing. If you're just painting it all free hand, paint choice is less of a big deal. Use really good exterior grade paints and you'll be fine. If you plan on using vinyl and masks, you need to be MUCH more careful. I recommend DTM paints. I've always used PPG but other brands work I'm sure. They're a mix between an enamel and a traditional latex paint. There are a bunch of HDU specific primers you can buy from your sign supplier. PPG Sure Grip also works well. There's another PPG fast drying paint that I haven't tried since I've been moving away from carved signs and that's Breakthrough. Dries way faster than typical latex paints.

But the #1 rule of painting HDU/PVC signs, above anything else, is let the sign really dry. You just can't rush it. Every time I have, I've regretted it.

 

[Krissy Louderback]

This is the primer I use from Tubelite. I use SW latex paints, 2-3 coats for finishing. Be sure to lightly sand your flat spots and then rinse the sign with water and let thoroughly dry before priming/painting.

 

[Chuck B]

The number one thing to remember about painting HDU/PVC is dry time and prep work.

If the can says dry for 6 hours, triple it. HDU and PVC do not absorb moisture. So all of the drying goes one direction. When you paint a wall or wood, it will absorb some of the moisture which makes the drying go much faster. So don't rush the paint.

HDU is also a material that needs to be really clean before painting. Sand it down to form a texture, blow it off, and then if you can, spray it with a garden hose. You want to get it clean as you can.

After that, it depends on what you're doing. If you're just painting it all free hand, paint choice is less of a big deal. Use really good exterior grade paints and you'll be fine. If you plan on using vinyl and masks, you need to be MUCH more careful. I recommend DTM paints. I've always used PPG but other brands work I'm sure. They're a mix between an enamel and a traditional latex paint. There are a bunch of HDU specific primers you can buy from your sign supplier. PPG Sure Grip also works well. There's another PPG fast drying paint that I haven't tried since I've been moving away from carved signs and that's Breakthrough. Dries way faster than typical latex paints.

But the #1 rule of painting HDU/PVC signs, above anything else, is let the sign really dry. You just can't rush it. Every time I have, I've regretted it.

+1 for the PPG Breakthrough paint...awesome!

 

[visual800]

blow it off real good as far as primer you can use a high quality exterior flat and spray it on possibly 2 coats of this. We use nothing but BEHR paints, they hold up just fine and NEVER use oil based

 

[Barry Jenicek]

Hi There,

Here is what I do when painting HDU with the simulated raised grains from my homemade “Grain Frame”.

After Sandblasting, I Blow Off the sign to get the dust out of the valleys. I get my blower as close as I can to the grains to make sure I’m getting all the dust.

Then I take a power washer and give it a good cleaning. Naturally, I do not get too close to the grains because they might break off. After the water bath, I sit the sign on end with the grains vertically. (Helps to drain the water) Again, I blow it off to get as much water off as possible. Then, I let it sit over-night.

I do not use any primer on my HDU, I go directly to the color I am planning to use. If you have ever painted a “grained” HDU sign before, you already know how much “fun” it is to get the paint down into the grain valleys…not to mention how long it takes.

By-the-way, I always paint the entire substrate before applying the Sandblast Stencil. (I use Porter Paints) The frame gets it color, the letters will be get their colors, etc. I make sure each coat is dry between coats. Then I apply my Stencil and weed the background.

After Blasting, and leaving the Stencil still in place, I use a Paint Sprayer. I spray a small section (about 2’ x 2’) of the grained area. Then, using a Stiff Bristle Brush. I “push” the paint into the valleys. I do this for each coat. I find this faster rather than dipping my brush into the paint can and applying it by brush only...takes too long.

Once that is finished, I remove the Stencil. The frame and letters already have their colors applied and the sign is finished.

This works for me.

Barry

 

[nickelartistic]

Just an additional option to keep in mind: After years of painting HDU in many of the same helpful ways already suggested here, I actually developed a good working relationship with a local auto body shop. I've had him doing all my HDU painting now and its been completely worth it for me. His spray room is is much more dust free than any place I have to work, we get a full range of automotive colors to work with, his guys do a much better job of cleaning it than I ever could, and most importantly the signs get a high bond primer, followed by an evenly applied auto grade enamel finish. He likes to do the work because its very straight forward and quick and what he charges me is totally worth the time I save not having to fool with things especially if I end up getting a run and and having to sand and repaint. I return the favor by helping him out when he needs custom vinyl striping, or other vehicle graphics. I loved the satisfaction of doing everything myself, and still do all of the finish work and leafing myself, but sometimes time and profit margin just don't let me do it anymore. Just a thought - good luck!

 

[CC-CMYK]

+1 for the PPG Breakthrough paint...awesome!

Have you used ppg breakthrough on acrylic letters and signs? Does it hold up well outside?

 

[Chuck B]

Have you used ppg breakthrough on acrylic letters and signs? Does it hold up well outside?

I haven't used it on acrylic, just dimensional urethane. I would think it would hold well to acrylic if you go over it with a scotch pad or use very fine sand paper to put a tooth on it.

 

[Evan Gillette]

If you have a full painting setup its hard to beat Mathews for overall finish quality and durability, I have a neighboring body shop do that for me if I need it. IIRC the primer is Mathews 6001 and SignBrad has some super good information on what his painting process is (use the search bar as there are several good threads about this topic).

If you dont have a booth and full setup you can do what others have mentioned with latex. I have done this as well with good results. For smaller panels you can get a $50 "paint tent" on amazon and use an airless sprayer, or if you have time just use rollers and brushes. For woodgrain you will probably have to do a bit of both. Signs By Van has some good videos on their youtube channel of this process. I like the Behr paint that they recommend but most brands have a high-quality exterior that will work well.

 

[Zac]

I used a Matthew’s system at a shop that primarily made ADA/Architectual signage. It was great stuff and their matching system was very easy to use.

We did have some trouble with their ‘Low VOC’ ADA clearcoat when it first came out. Boss was trying to be eco-friendly but we had to switch back. It was just too inconsistent.

 

[signbrad]

HDU is an amazing product. It will accept any type of paint. If left unpainted, such as on the back of a sign, it will turn color but it will not rot. It lasts forever.

The Matthews 6001 Primer-Surfacer was developed specifically for HDU. It dries quickly and sands beautifully. You can roll or brush it, but spraying is best. Use a big tip (I use a 2.0) and clean your gun religiously (or keep a rebuild kit on hand.) It can even be used to fill dings and gouges if you let it set up in a paper cup and use a putty knife. It smells EXACTLY like Bondo. I think you can top coat it with anything. You can get an almost glass-like finish using car paints, if that's what you want—I can make a slab of HDU look like real marble.

Brad in Kansas City

 

[Gino]

Many many years ago, I was visiting a shop in another state who majored in HDU signs. They told me, the sun will kill bare HDU. Ya need to make sure it's completely covered and covered well. He said, they get more work from repairing these signs because of stones or whatever hitting these kinda signs and chipping the paint off and the sun will eventually burn a hole in it. You're saying this isn't so ?? I'm questioning, as I never had it happen to me.

 

[gnubler]

I removed this old sign from an install I did - this is HDU, correct? The HDU I've worked with recently is a blue-ish color. All the areas that were damaged and had paint removed got really crumbly and orange as you see. The lighter area is where I gouged it out to see what the material actually looked like underneath.

 

[signbrad]

Many many years ago, I was visiting a shop in another state who majored in HDU signs. They told me, the sun will kill bare HDU. Ya need to make sure it's completely covered and covered well. He said, they get more work from repairing these signs because of stones or whatever hitting these kinda signs and chipping the paint off and the sun will eventually burn a hole in it. You're saying this isn't so ?? I'm questioning, as I never had it happen to me.

I have left HDU unpainted in the weather and never seen it fall apart even after several years. The surface discolors, but the discoloration is only an eighth of an inch thick. The sun can burn a hole in it? Maybe the brands vary in their UV resistance. Maybe the density makes a difference. Yes, HDU is kind of crumbly by nature. And I noticed scraps that looked bad after a long time, but when I cut them they looked okay on the inside. If someone has actually seen the sun burn a hole through it, that's a new one on me. But my experience is anecdotal at best. I believe that Coastal Enterprises merely claims that it "lasts ten times longer than wood."—part of their lifetime guarantee.

I have always painted it completely, anyway, on signs. It looks yucko if you don't. And it will try to warp if it's only painted on one side.

By the way, my dad was a pattern-maker (like a tool maker). HDU is used in foundry patterns and has been around a long time. It is waterproof, very stable, and highly heat resistant. Laminations of it are baked in autoclaves.

Brad

 

[Notarealsignguy]

I wouldn't use a latex paint. That's a dime holding up a dollar. Brad is correct. That primer sounds like slick sand.

 

[tbullo]

I have seen unpainted HDU( sign foam 1) turn a burnt orange color and when you touch the area it turns to powder. But this was the old stuff. As stated, always paint both sides.