The black background on this sign is vinyl film. The top molding helps prevent cupping on a hanging sign.
The graphics on this sign were router-carved through a black vinyl background then finished with 1 Shot Metallic Brass enamel.

PVC can help you offer an affordable 3D sign

By SignCraft Magazine

Posted on Tuesday, April 21st, 2020

Often a client would like a 3D sign instead of a flat sign but just can’t stretch their budget for it. Or they came to you wanting a full-blown 3D version of their sign but the cost is out of reach. The HDU substrate, the priming and painting—it all adds up, increasing the cost. That’s when Mike Keene offers a version on 3/4-in. PVC board. He routs the graphics and uses vinyl film for the background. 

“This approach means less material cost and less time,” says Mike. “I can still give them a nice-looking, affordable 3D sign. It makes a great upsell from a flat sign, too. V-carving has a lot of appeal. I often use Metallic Brass 1 Shot enamel instead of gold leaf on the lettering or border for a classy look.

“Using vinyl for the background cuts production time and reduces the cost for the customer. And if you use a white border, you can just peel off the mask, finish the edges and it’s done. PVC is affordable and durable. It has its limitations, but I work around them.”

Upselling like this is one of the easiest ways to boost your bottom line. You don’t have to find a new client to sell a sign to—you’re just increasing the dollars that come from this client. And when you get more of these upgraded signs out there, they will bring you more requests for high quality work. 

Mike applies 3M high performance vinyl to the background area of a panel of ¾-in. Komicel PVC board using wet application to avoid bubbles. He leaves a border, and lets the panel dry overnight. The next day, he masks the face and does the routing using a conical or v-carve bit in his CNC router.

“You can’t rout through the vinyl with an end mill bit,” Mike says. “Its straight sides will tear up the edge of the vinyl film. A conical bit cuts at an angle and cuts the vinyl cleanly.”

Once routed, he removes the mask. If he is leaving the border of the sign unpainted white PVC, Mike primes and paints the edge with white exterior acrylic paint. Otherwise, the somewhat rough edge of the PVC may grow black fungus or mildew.

If the border or other areas are to be painted, he cleans then scuff sands them. Next, he rolls on a coat of Grip Gard VPS primer, going over that with a foam brush to eliminate any bubbles. He then brushes on a coat of oil-based primer, because it’s easier to sand than exterior acrylic primer. Then it gets sanded and finished with either oil-based enamel or exterior acrylic paint.

Here are Mike’s tips for getting the most out of routed PVC signs:

All PVC doesn’t behave the same. I find that Komicel PVC gives me the best results.

Before I apply the vinyl or do any painting, I clean the PVC with isopropyl alcohol or lacquer thinner.

Latex primer and paint will adhere to the edges of PVC but not to its smooth surface. Grip Gard VPS Primer from AkzoNobel adheres well to all surfaces of PVC, then you can apply oil-based or acrylic finishes over it.

After the Grip-Gard VPS Primer, we usually brush on an enamel primer. I prefer that over acrylic primer because it’s easier to sand and the mask peels off cleaner. With acrylic primer, the mask may tear up the edge of the paint.

Since I am usually using PVC to manage costs, these signs usually don’t get gold leaf. Instead, I often paint the letters or other graphics gold. I apply a base coat of yellow enamel over the VPS primer. Then I spray on a coat of 1 Shot Metallic Brass enamel.

As with aluminum or plastic, a dark color background on PVC may cause expansion issues. For this reason, I don’t use PVC for huge signs. Most are relatively small. I’ve done PVC signs like this up to about 4-by-6-ft. using a dark background, but they have had a substantial white border.

If you screw PVC securely to a flat surface it may “oil can” or warp between the fasteners. To allow for expansion, I usually bolt it without drawing the bolts tight and use a slightly oversized hole.

For double-faced signs, I sometimes use 1-in. PVC. If you carve only one side of a ¾-in. panel, you can get cupping, particularly if it is a hanging sign and you remove a lot of the background.

This approach only works when you do the routing with a conical or v-carve bit. An end mill cuts at 90 degrees from the surface of the panel and will tear up the edge of the vinyl that you applied to the surface of the panel for the background color.

I use only 3M high performance vinyl on these signs. I tried translucent because it has a matte finish, but it tends to peel off the PVC over time.

Be sure to check out the feature on Mike and his work in the November/December 2019 issue of SignCraft