Spraying Sign Prime onto 3D reliefs

[mountie1808]

Now that we're doing a lot of 3D work on our router, we're running into a problem of finishing them in a reasonable amount of time. My question is this: Is there anyone out there spraying SignPrime onto their sign foam signs? We're not wanting to go the brush route with everything and are also leary of the thickness of the primer taking away from some of the detail. We're currently running an HVLP (I think I got that right) system but do have the other types of sprayguns as well as air brushes. Is it just a matter of nozzle size for the gun? If so, what seems to be working for other people? Is there an alternative to priming signfoam with signprime?

Any thoughts, comments, or suggestions are most welcome.

Mike

[Brady Watson]

I've thinned FSC-88 WB with water (about 15-20% water) and mixed with one of those hand blenders that people too lazy to beat eggs with a fork use...It sprays fine in a harbor freight HVLP gun. The key is thin coats. You'll need about 3 or 4 to get somewhere with it & be sure to get a fan on it as soon as you are done spraying. Make sure it is dry before re-coating.

-B

[joe]

Michael,

I'm with you when it comes to loosing detail with thick primers. Thinned down primer means more coats. You end up loosing detail.

Have you considered using a higher density Material. 20, 30, or 40 HDU requies little or no priming.

There's a cat down in Texas, I think his name is Chapman or something like that, who uses 20lb and doesn't prime at all.

Joe
www.normansignco.com (http://www.normansignco.com)

[mountie1808]

I'm not sure how cost effective using a higher density sign foam would be. Seems to me that we're using 18 lbs. foam now. The multiple coats with dry time puts us right back to where we are hand brushing the primer. The only advantage would be the benefit of not losing as much detail.

Thanks all,

Mike

[jamesgilliam]

Mike and Joe, I have done a couple of signs spraying primer with no loss of detail. Last sign I switched material to Corafoam and did not have to prime at all. Their 15# is equal to 18-20# precision board, and you don't get the gritty feeling from it. Thanks again to Ray for bringing samples to the Austin camp, that is what got me started in signs.

[joe]

Michael,

I think most of are at a loss about the amount of detail you are concerned with.

It should be noted that 15lb foam has a difficult time carrying the detail a 20lb foam is capiable of. There's also a cost savings with finishing time.

Perhaps you could post an example of your project.

[mountie1808]

I'll do that when I have a chance to get back to it. Right now the only things we have going are big jobs where the time to brush the primer is no big deal and the details are large enough that detail loss is not an issue.

Mike

[joewino]

Michael - we use 20# Corafoam for anything that needs to have some fine details and then spray water based paints with a HVLP gun. Sometimes if the items are really small we just use a spray can from Lowe's and do not use any primer at all.

The primer does not make the paint stick any better to HDU but only makes it smoother. Any paint will stick to HDU without a primer, if you remove all the dust before painting, either with compressed air or a strong stream of water.

[mountie1808]

One of the problems that we're running into is that the paint actually etches/textures the foam. Again, I'm not sure what weight foam we're using since all I'm doing is grabbing scraps that are laying around the shop to play with. I don't have the same problems when working with either redwood or cedar.

[jhicks]

Something NOT right about this last comment. Primer "etching the HDU foam?" Are we sure we have HDU here?

[joe]

Jerry,

Perhaps Michael is describing the resistance of HDU to accept thin latex primer. The less dense HDU has more larger michro-scopic holes making it harder to cover.

To retain reasonable detain on 15lb foam, I use Precision board 88 as it comes from the can. It's thick. I initially moosh it on the surface with a 1" fitch. Then come back and smooth it out with a soft bursh and a little spray bottle.

[mountie1808]

Ah, the paint was etching, not the primer. It could very well be the type of paint they were using. Whatever it was, it was not compatible with sign foam. No matter, though. The things they were spraying were just samples that I've cranked out as I continue to explore what it is I can do with my 3D router. My goal is to get to the point where I create most pieces seperately and then pocket them into the background. We're looking at orders where we'll have 50+ details that get dropped into other pieces. Cranking those 50 pieces out of a sheet of foam, priming, painting, then inlaying is what prompted my quest of spraying as much as possible.

As far as the reasonable results with 15 lbs foam, your solution puts me right back on the question of spraying a primer before coming back and spraying the paint. If you haven't noticed, I'm just very anti-brush. I suppose that's why I'm all about cranking the stuff out off the 'bot and letting someone else finish it.

Thank you all for your comments and suggestions, they are most appreciated.

Mike

[joewino]

Normally, HDU will accept just about any type paint without reacting to it, even the hotter two part automotive paints.

Are you sure that it's HDU?

We spray a lot of our HDU but use latex paints and a primer is really not necessary.

[joe]

Michael,

Please keep us informed on what paint will etch HDU.

Like Ray says, you don't have to prime!

[ernie_balch]

I have tried a wide range of paints on HDU and never had anything attack it.

I do remember the first time I sprayed it with Krylon and found out that the paint made the texture show up. HDU is nothing more than a sheet of bubbles, hence the name "signfoam" We always coat with a high build primer then sand it to get a smooth surface. The other alternative is to buy a higher density material that is made of smaller bubbles. Then you can skip the primer like Ray does.

ernie

[joe]

I agree with Ernie.

HB Primer, diluted correctly, reduces the finishing time.

For a light attractive texture I use PB's Crack Filler, applied with a brush and lightly sanded.

J
6033

[bleeth]

I used to use Duratec on boat plugs-Expensive but great to sand.
What's PB stand for Joe?
Edit-Uh OH-I tink I know!!

[joe]

Hello Dave,

Pardon the abbreviation. It's "Precision Board" and I recommend their primers, fillers and glue.

The "Crack Filler" works well as a primer as well as a texture material. To prime a flat sheet of HDU, I apply a fat glob and spread it around with a big squegee. This takes very little filler and leaves the panel very smooth. The excess is guided back in the bucket. Keep in mind, you are only trying to fill the micro-scopic pin holes.

I picked up this technique while in Scotland at a Letterhead gathering. Well, the truth is, I stole it. Since the crack filler is the consistancy of Yogurt, it stays put and dries fast.

The sample letter below is a combination of Crack Filler for a texture and a Sculpt Nouveau copper finish.

Good luck.

J
www.normansignco.com (http://www.normansignco.com)
6034

[jhicks]

Nice work as usual Joe.
Love that textureing but its the creative design thats realy impressive.

[joewino]

Nice looking work for an old guy.

[mountie1808]

What about spraying a two part hardener? Or do I run the risk of quickly clogging my spray gun?

Mike

[ernie_balch]

If you don't want to sand you can cheat and get a smooth surface. You use a 2 part epoxy like a thick paint. The viscosity is similar to honey, and it will drip (so plan for it). The surface becomes very smooth which is nice for doing gold leaf. We usually add a little one shot for color. The HDU vendors actually sell a material for this purpose although we have found other materials work just as well.

ernie

[mountie1808]

What about putting a hardener on large signs? If I were to do a 5' x 10' x 4" sign out of signfoam, complete with textured background, is there anyway for me to put a protective hardener on it so that it's more resistent to damage from simple things like something banging into an edge? That begs the question, then, about just putting a hardener on the edges to protect the corners.

Any thoughts?

Mike

[Brady Watson]

Epoxy or FSC-88 + epoxy.

-B

[bill.young]

A word of warning before you cover your sign in epoxy. Some epoxies can cause problems with paint curing because of an amine "blush" that appears on the surface as it cures. Oil paints are the ones that seem to have the most problems...I've had some that stayed so gummy that after a week I could scrape the paint off with a putty knife.

I'd recommend trying a sample before covering your whole sign. The amine is water soluble so can be washed off with fresh water and a scotchbrite pad, but that's not something you'll want to do on a large foam sign.

My only experience is with boatbuilding epoxies including WEST and MAS though...your mileage may vary.

Bill

[Brady Watson]

Good point & advice, Bill...

[joe]

When HDU first found it's way into our shop there was a considerable learning curve. Our first lesson: HDU doesn't work well with screws and doesn't like to be glued to wood.

Fabrication is done with glue only. Our HDU post are even glued to the body of the sign. I know how well it work but still there should be some bolts.

Like Michael says, they're more eality damaged during transportation than good old redwood. Once in place however they seem to last and last without much care. We experimented with several types of hard coats. Styro Spray makes a brushable top coat #517 and Demand Products also offers several others. Their Eurea type hard coat works very well. It's all too much trouble though. 15lb HDU is good to go as is.