I've always been a wood man and have only used HDU in the form of carvings that I attach to the wood...I've always finished the HDU just like the wood...prime and paint...the other day I was visiting a local sign shop where they were painting a raw HDU sign without priming...I questioned them and they said HDU didn't need priming...this sounded strange to me so I thought I would ask you guys since I'm doing my first HDU sign...it is a double sided 4.5' x 8'...I want to do it right...what do you guys say.
[ February 06, 2009, 09:23 PM: Message edited by: Rusty Bradley ]
Posted by Chris Lovelady (Member # 2540) on :
Rusty, i say yes you need to prime. you will need a high build latex primer like jay cooks primer. now there are some high end paints like Sherwin Williams Duration that claims to be self priming but i have found that you need to prime HDU. also wash your panel off really good to remove the dust berfore priming.
Lovelady
Posted by Dan Sawatzky (Member # 88) on :
I spoke whith Gary Anderson regarding this subject and he tells me he does NOT use primer on his HDU signs. He used acrylic paints exclusively.
We also use acrylic paints, but do use Coastal Enterprises heavy bodied primer on pretty much everything we do. We also use 30 lb Precision board which has virtually no pinholes like the lighter weights. The primer in my view gives a better finish and brighter colors with less work. On many occasions we will add more than one coat of primer to areas like lettering and borders so we can add subtle texture with a brush. Under gold leaf the result is spectatular!
Getting rid of the dust like Chris days is critical... as is using a fan to dry your work after priming but before final finish coats of paint.
Coastal Enterprises has some short videos on their site for training regarding the use of their glues and primers which are worth the time to watch.
Primed and ready to go in Yarrow...
-grampa dan
Posted by Kelly Thorson (Member # 2958) on :
One of my concerns with not priming HDU is that my experience is it does degrade with UV exposure. For that reason a coat of primer seems like added insurance. Posted by Amy Brown (Member # 1963) on :
We only prime signs that need a good smooth finish for applying paint mask (example: v-carved letters).
I have not seen any difference in the signs that are primed versus not primed. Many have been up five years or more.
You just have to use a good acrylic paint. I think priming is a waste of time and money on most projects. Haven't had a failure yet from not priming.
Like those above, we clean with a high pressure waterhose and then make sure it is completely dry.
[ February 07, 2009, 07:56 AM: Message edited by: Amy Brown ]
Posted by Dale Feicke (Member # 767) on :
Rusty, HDU is a different animal altogether. It is not porous, like wood and does not "soak up" paint, although it does have the tiny foam bubbles. It just needs something to "bite" into the surface. That's why it's important to wash and/or blow off well to get the dust out of the foam so the paint can grip solidly. I really can't tell any difference between primed and not, so I guess it's up to you.
I do usually always use an acrylic primer. From that point, I'll use either acrylic or oil base.
Posted by KARYN BUSH (Member # 1948) on :
i say prime...and i personally like the signfoam primer...its not thick like the others...goes on more like heavy cream. of course this is only personal opinion...but its mine. Posted by Tony Vickio (Member # 2265) on :
The best primer I have used on HDU is Omni MP243 Polyester Primer. It is a two part mixture. I use a squigee to "push it" into the foam. One coat! Can be sprayed, brushed or "pushed"!
Posted by Raymond Chapman (Member # 361) on :
Ah...the age old question - To Prime or Not To Prime.
As you have already seen, you will get as many different answers as there are folks who post an answer to your question.
This is what we have been doing for years with no failures:
Since the HDU cannot absorb anything, including the paint film, almost anything will stick to it. Mr. Sawatzky mentioned Gary Anderson, whom I consider to be the guru of all things signs. He does not prime but uses 100% acrylic paints for everything he does and with no failures for the past 20 years or so.
One of the secrets is to use the very best paints available, and to me that means Porter 100% acrylic, although we do use Sherwin Williams Super Paint sometimes.
The only difference that I can see in primer or no primer is the paint finish texture...but nothing to do with the way the paint sticks to the surface. We like a really smooth finish and so we either have to build up several layers of paint or use a high build primer. For the times we want that super smooth finish (signs seen up close or those that require gold leaf) we prime with Coastal Enterprises FSC-88-WB water based primer/filler, applied with a HVLP spray gun.
We do all of our blasting, routing, carving, etc and then apply primer and paint.
So, the simple answer seems to be....do whatever you want - prime or don't prime, and it will make no difference in the adhesion of the paint.
Just be sure to get rid of all the dust - we just rinse everything with a garden hose and high pressure nozzle.
Posted by Jackson Smart (Member # 187) on :
We also do a lot of HDU signs.
I always use a primer. I fisrt cut the design from raw HDU. Then I sand the entire sign and then prime.....paint/paint. Then I put on pattern and then mask, then cut out and remove where needed. When it is blasted it will eat thru the paint and primer then in to the HDU.
When I strip off the mask I already have it painted. Then I can paint with the proper colors. I also do the background color before I pull the mask. Then a light sand on the painted surface and away we go.
The backsround color is made from one-shot lettering enamel or comprable paint (Pittsburg or Pratt Lambert) and mixed with flatting paste to achieve a nice flat surface.
...we seem to get stuck in what works for us.... Never had a failure so far....I guess that says something.
Jackson
Posted by Rusty Bradley (Member # 6938) on :
Thanks guys...this takes the worry of doing something wrong away...sounds like I cant go wrong either way.
Posted by Jay Allen (Member # 195) on :
Kelly Thorson is correct . . . UV does degrade the paint on the TOPS of the signs and dimensional letters. (probably snow and rain don't help either)
You don't NEED to prime HDU - but priming any horizontal surface will serve you quite well . . .
We've seen the tops of HDU signs and letters fail (even with our standard 3-4 coats of acrylic) after 4 years or so.
Vertical surfaces? Not needed.
Horizontal? Go look at some of your old signs without primers . . . you won't believe how much the paint degrades on a flat, horizontal surface.
Posted by Kellie Miller (Member # 2788) on :
Hi everyone,
Kelly Thorson and Jay Allen are correct. The only thing that affects HDU is UV. The reason for priming (besides a smooth surface) is to make sure that your HDU is completely coated. Because it's a closed cell product (doesn't absorb anything, which makes it completely waterproof) not everything adheres to it for the long term.
Gary Anderson does use an acrylic based paint with no primer, and he's done a lot of testing with it so knows it adheres for the life of the sign.
Jay is right, if you don't have your sign completely coated, you will notice a deterioration behind the paint.
Priming is inexpensive insurance that your paint and HDU sign will look great and last indefinitely.
We manufacture FSC-88 Water Based primer/filler and have a free training video on it for easy use. It is higher in solids and if you want a creamy consistency, which Karen mentioned and how we recommend using it, then reduce with about 2% water. It runs about $40.00 Gallon, which is less expensive than other high solid primers.
If anyone has any questions or would like to try a free pint sample of the FSC-88WB, or a CD of the training video, please call or email.
Thank you, Kellie
Posted by Kellie Miller (Member # 2788) on :
P.S. Sorry Karyn, I spelt your name wrong!! (and I know better..)
-Kellie
Posted by Raymond Chapman (Member # 361) on :
Hey...now you know what is best because you've heard it straight from the hors.....straight from Kellie. And she's the expert.
If Kellie says it works or doesn't work you can bank on it.
Posted by Jay Allen (Member # 195) on :
Hey Kellie girl . . . I miss seeing you. We're thinking of going to the NBM show in Indy this year. Would you be going? If so, would love to go out to dinner and make a fool of ourselves . . . again.
We've used FSC-88 for about 10 years or so. The high-build solids (actually sands out really well once dry too!! for those 'glass finishes') really make a difference on the horizontal surfaces. We spray less heavy on the faces (except on lower density HDU's - we use a LOT of primer on that) and more on the tops of the signs and raised surfaces . . . and it DOES make a huge difference.
Ray . . . got your check. Thank you. Don should have his tomorrow or Friday for almost all the balance (still waiting on some) . . . nice total, it wa$ . . .
Posted by Cam Bortz (Member # 55) on :
Rusty, the commentary regarding whether to prime or not to prime is all good. But another comment I might add is toward the construction of the sign itself. You mentioned that this is your first fully HDU sign and it is double faced, 4.5x8'. If you have not already done so, I would strongly urge you to build this sign with back to back faces, using an internal support structure of some type.
Again, if you are already doing this, never mind. I mention it because I've seen newcomers to HDU (myself included!) make the mistake of using solid two-inch thick HDU for double faced signs, only to find out the hard way that such signs are vulnerable to breakage from relatively minor impact shocks.
Finishing, whether primed or unprimed, is important, of course. But the most beautiful finish won't protect an HDU sign that isn't built according to, and being aware of, the limitations of that material.
Posted by David Wright (Member # 111) on :
Trust Cam on his advice, I learned the hard way last year on what not to do.
Posted by Kellie Miller (Member # 2788) on :
Thanks Ray and Jay~ :-)
Rusty, Cam does make a very good point, in one subject that wasn't addressed. When it really comes down to it, the way the sign is strengthened and mounted is really what will make it last. (Hi Cam!)
Great ideas everyone! (Jay I miss you too.. not sure about Indy, but we will catch up soon.. whether it's around a giant cow in WI or a German restaurant with Butch Anton and sausage.. ew) haha!
Take care, Kellie
Posted by Rusty Bradley (Member # 6938) on :
Cam...thanks for the advice on internal support structure...I did however construct it with that in mind...I used 2 one inch HDU panels with an MDO center...the sign is 2.5" thick...the picture below was taken before the final top 1" piece was glued on...the other picture shows after blasting with my homemade grain frame...another first...I liked the grain pattern ok but will fine turn it a bit more with some curvy bends and a small knot or 2...thanks everyone for the advice...muchly appreciated.
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