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John Yarnell's notes:
When I started this thread the only response I got for a while was from Mike Jackson who pointed out some problems with my techniques that might have lead to the peel up on my last few signs. (Thanks Mike) He mentioned that I probably beat up the signs with a grit of sand to course for the wood. The other was the grain this I’m sure for most was a common sense thing but until Mike pointed it out did not really dawn on me. I have always liked the look of a more horizontal grain when sandblasted but Mike pointed out to me that it can lead to pull up problems due to the way the grain is laying, each grain on top of the next to the face of the sign.
Well first I’d like to say thanks a bunch for everyone’s advice and experiences they shared. I got in to this project around the same time I started this thread. I made up three 4’x8’ redwood blanks about a year ago. This was the last of the three I made. I saved it for last because of some pretty sizable cracks that ran about half way through the blank.
The blanks are not traditional as far as I know. When I made the blanks I was trying to find a way to create a less expensive redwood sign. I laminated 1â€x8†redwood to ¾†plywood. I hope this does not prove to be a mistake but so far seems to be holding up very well.
The resin when in its liquid state really soaks in to the wood and when hard bonds that top layer of grain together. When I came in the next morning after flooding the surface it was one of the glossiest finishes I have ever seen on wood. I really did not want to move forward to the next step after getting that glossy finish on the redwood.
With this sign I had to use the same wood I have used on the last few signs so I decided to try something new. I have been using epoxy resin to fill in any cracks in the wood. With my new knowledge on the grain of the wood I was pretty worried about pull up and have never done a sandblasted sign without the finish first method. I decided to push forward; in the place of Sign Life and Sanding Sealer I flooded the face of the sign with West Systems Epoxy Resin 105.
I roughed up the surface pounced my pattern and painted the colors in the appropriate places. When the One Shot dried it took on the same gloss the resin had. It kind of looked like an automotive finish, it was nice! I did have one problem with the paint. I decided to take one more step to prevent peel up. For the first time I added One Shot hardener to the paint. With the black paint I had a few spots in places that took three days to dry?
After an extended wait with all the paint finally dry I applied sandblast mask and cut it to the pattern. I blasted next and had no problems there. I did have an interesting thing happen while blasting. The resin put up quite a fight in places and I think added in a positive way the patterns in the wood after blasting.
I painted the background with a solid stain while the mask was still on.
Next I crossed my fingers and started to pull the mask…. It worked! It all came off without a hint of peel up.
So I finished up with the lettering and cow that were thermal prints from my Summa DC3.
Sorry for the long post but I wanted share my experience. I think on my next sandblasted sign I will try the unfinished method. Is that what it’s called? Well if all the talented sign guys that have posted here unanimously say they don’t like the finish first method than I’m listening. Any comments, advice or criticisms are welcome.
John,
Thanks for taking the time to shoot the photos and supply the text for this thread.
Assuming you want to hear them, I have a few comments, not meant to be critical, but more to inform anyone interested. I see a few red flags on this project, even though the newly finished product looks great.
1. From what I can tell, it looks like you laminated the thinner redwood onto a piece of plywood or MDO (you say to save money). Taking everything into consideration, I doubt you really saved too much money. Since plywood is stacked with alternating grain directions, it is usually fairly stable overall. Redwood, on the other hand, likes to swell and shrink as the seasons pass. I've seen a 4x8 redwood panel shrink as much as 1/4" in length and 1/2" in width. You may have a bit of a time bomb on your hands.
2. I've have to question the choice of wood. From all I ever read on the subject, horizontal grained redwood is preferred to flat grain for a couple of reasons. Vertical grain wood usually gives a better grain pattern when sandblasted and it typically more "stable" (contraction and warping). Horizontal grained wood can cause problems when sandblasting, especially if you blast down into a particularly hard and stubborn growth ring. Horizontal grained wood will usually want to warp in one direction or the other. For redwood decks, the plans usually suggest turning a horizonatal grained piece of wood so the end grains look similar to a rainbow, and not a smile. The wood will usually bow so the center of the board rises, while pressing down on the bottom edges. This is to keep the deck from having too many raised lips to catch you feet on. For laminated panels, most books I ever read suggest you alternate the grain directions on horizontal grained wood so you get a "wave" effect when looking at the ends. Instead of a panely trying to make one huge rainbow bend, it would naturally stay relatively straight with mini wave bends.
Also within the wood choice topic, most people like "clear, all-heart" (vertical grain) redwood. Clear pertains to the amount and size of the knots, and all-hear revers to the all reddish color. The white redwood is called "sapwood". It is usually cheaper and I suspect most of that has to do with the fact is is less rot resistant for decks and other outdoor projects. When fully sealed and painted, I doubt that makes much difference...but it is worth mentioning. Additionally, I'd point out the obvious: A board that has a crack in it when you buy it will always have a crack in it. I would have left that cracked board off this panel at all costs and used it for a trellace or framed edge board. That crack cost you an additional day, plus once it was filled with epoxy, it showed rather bad in the final sandblasted background. You may have had to grind/chisel it off before finishing the sign.
3: While you may have solved the issue of the horizontal grain lifting when you peeled the stencil, I would be a bit spooked to pour epoxy on the surface of a piece of "live" redwood, especially spanning that much area. Epoxy traditionally cures as hard as a rock, but the wood under it will be wanting to shrink in the heat and low humidity periods. Time will tell on this project...keep us posted in about 6-8 months.
4: I have never been a big fan of spraying paint on the background of a sandblasted sign for a couple of reasons. First, to go through a normal spray nozzle, the paint has to be thinned considerably. It will not be quite as strong as if left full strength. Second, the spraying process more or less dictates that you spray a lot of paint straight-on, but less along the "sides' of the open end grain of lettering, graphics and borders—the place you need the most paint—not the least. The other problem with doing the "finish first" method shows up if you opt to hand paint the background with a thick bodied latex paint. Paint will actually build up along the edges of the stencil, and when removed, leaves a ragged edge of latex paint.
5: As you mentioned, you can end up with a LOT of time waitiing for undercoats to dry. On most finish first panels, you will have severa days or even a week from the time you cut out the panel until you have a chance to apply the stencil. Of course, IF you do have a pull-up, the perfectly smooth background now has more problems to deal with.
For my time and money, the process just doesn't make sense in the long run. We haven't made a sandblasted sign in 10 years now, but we made a lot of them when we still owned the shop. Here's my logic: I could take an order and laminate the panel on the same day. I could sand the panel in the morning, cut it to shape and (laquer sanding) seal it before noon. I could apply stencil after lunch, cut it and blast the sign in the mid afternoon. I could peel the stencil and sand the panel smooth again later in the afternoon, and get one good coat of latex paint on the front side before going home. The next morning a second coat, and depending on the time of year, another coat before lunch. If the fourth coat was needed, fine, no problem. By the end of the second day, my panel is ready to start decorating with gold leaf, letter colors and so forth. Many of our signs had two or three additional coats of a latex border color, which added to the paint on the end grains of the sign and border. That could be done quickly with latex.
Even if we waited until the third day, we could apply gold size in the coves and first coats to all lettering and graphics. Occasionally, we used a 50-50 mix of blockout and enamel for the first coat so it would dry faster. Within an hour, we had leaf in the coves and were ready to apply the topcoats where needed, usually right after lunch on the third day. By evening, we would have been detailing the pinstripes and outlines.
Somewhere along the way, we would have painted the back side of the sign with the same color of latex paint we used on the ends and border, normally three to four coats of latex paint.
Going back to my comments about spraying....we almost always painted out latex backgrounds with a 3/4" x 1" "fitch". It sounds small, but it can push a lot of paint around on a latex background with sandblasted texture. The small paint brush allowed us to push and deposit paint into all crevices and along the sides and edges of the raised elements. When you drag your brush along the face of a letter, it will automatically squeegee paint off the brush and along the sides of the end grains, giving you plenty of paint build up. You simply dry brush the surface a bit once the paint has been applied over the region. The first coat takes the longest and uses quite a bit of paint. Second, third and fourth coats go much faster. In the end, the final surface probably won't be as glassy smooth as your sign, but it will certainly out last it, and the surface will be plenty good for any sign customer I ever dealt with. I never tried spraying with a HPVL (high pressure, low volume) system. I suspect it might do a better job of spray painting, allowing you a better build up along the edges of the open end grain. Others might have more experience on that topic.
The timing example above would not necessarily be typical, mainly because we sold quite a bit of sandblasted signs and blasted all of them at the same time, sanded at the same time, and generally finished them at the same time. With that said, we did rush a job when necessary and the timing is pretty close in those instances.
I offer the comments above to at least provide some insight to anyone else interested in trying a "finish first" sign. We had much better "luck" blasting first and finishing last.
Mike Jackson
Mike Jackson / co-administrator Golden Era Studios
Vintage Ornamental Clip art
Jackson Hole, WY
Well that’s not going to make me sleep perfectly tonight but if the sign does go south it will be one expensive but worthwhile learning experience. That’s the reason I love letterheads. Taking the time to write down my process and take some pictures to share with you all gives me a chance at that one thing I regret most about starting my shop when I did. I wish I would have taken the time to do an apprenticeship in a real sign shop. I can’t turn back the clock however all is not lost. I’m lucky enough to have you all stand over my shoulder and generously give me professional tried and tested advice.
Mike thanks so much for your time you must have spent at least 2 hours between helping me with my post and responding with all your tips and methods afterwards. I won’t try to defend any of my methods that I used on this sign only because it’s the best way at the time I knew how to do it. I do know this now I will use the traditional method or finish last on my next sandblasted sign. I will probably print out Mikes post and use it as a step by step. Again thanks and any other advice or criticisms are welcome.
Our methods may be just like everyone else, but they may be helpful to some beginners.
First of all, I must admit that most of what we do I learned from Mike Jackson. It was my good fortune to be able to work with Mike and Darla on two ocassions and I found out how hard they had to work to make a success of their business.
Most of the time I say that Darla does all the work and Mike just signs autographs and talks on the phone, but that is just my way of poking at Mike some. Actually, they both are extreme in their approach to whatever they do.
At the time I worked with them I was employed by another sign company doing design work and hand lettering. I didn't have to install anything. Mike found out quickly what a klutz I was at installations. Now that I have my own shop I have progressed a little with my abilities concerning installations.
We apply the mask (Anchor #111) directly to the redwood or HDU. (We are just completing three redwood signs today.) A full size paper pattern produced by the plotter is attached to the mask using 3M #77 spray adhesive. The blank is just a rectangle at this point - it is cut to shape after the sign is blasted. This prevents getting any dings in the edges while moving it around.
The mask is cut with an X-acto or if the copy is very small we may cut that on the plotter and then place it in the correct area. Most of the work we hand cut.
After blasting, we cut the blank to shape while the mask and pattern are still attached.
The mask is removed and the surface is sanded with either a block sander or random orbital - 220 grit. Coves or other treatments are then routed or carved.
After a careful cleaning with air we cover the entire surface with primer. On redwood we use a Sherwin Williams oil based primer made for redwood and cedar. On HDU it is FSC-88 WB from Coastal Enterprises. Like Mike, we have never had success spraying redwood, although we use a HVLP spray gun for the HDU.
When the primer is dry, we sand lightly and then apply two coats of 100% acrylic latex paint. Some areas receive as many as four coats.
I've tried the paint first method and just never really cared for it. The paint has peeled up several times and then it just doesn't seem that there is enough paint right at the edge of the mask where the lettering and background meet. I just like the idea of a continous paint film over everthing.
When we were gluing up our own redwood we put a spline between each board, but now we get the blanks already together from a supplier, although we seldom use redwood any more. The redwood job in the shop now was specified by an architect.
I agree with Mike about adding a plywood or MDO backing to the redwood. While I have never done it myself, I have seen signs that were done this way, and they failed over a period of time. The wood has to be able to expand and contract.
I also like to see explanations for certain decisions rather than "here's what we did".
For instance, the primary reason for using an alkyd - or oil based primer on redwood is to stop the migration of the tannic acids in redwood that come to the surface after priming. In fact, we tint our white primer with dark brown primer and get a grayish color that stops ALL tannic acid leaching. Just white oil primers won't always do that.
Everybody has slightly different spins on how they make any sign - but, like Ray, most of my best info has come from Mike's articles - with fine tuning along the way that works with what we have experienced. Thanks for all the mistakes I did NOT make, Michael.
But you're right on target, John. Letterheads takes the pain out of the lessons to be learned. Better to walk in the snow in somebody else's tracks then to get your feet wet making new ones (at least most times).
Thanks for your input and advice. A few questions if you don't mind. Raymond after you prime a redwood sign with an oil based primer you use only arcrilic latex paints? Is it for the entire sign or just the background area?
Jay could you please give me a little more info on migration of the tannic acids in redwood? I have never even heard of tannic acids let alone there migration.
John - the entire sign is covered with 100% acrylic paint. We use Sherwin Williams Super Paint some, but mainly it is the Porter brand that we get from Rhino Paint Company (Gary Anderson). This is used for the lettering, trim, and inlines - everything. On HDU we use an HVLP spray gun to cover the entire sign with the background color, and then come in with brushes and finish the trim, copy, scrolls, etc.
Not to jump on Jay's toes, but the tannin in the redwood will work its way out of the wood right through the paint and leave dark stains on the surface of the sign. The primer that Jay mentioned prevents this. I suppose that something like Kilz would also work. I've heard that shellac also stops the process.
Since we use redwood only sparingly now, we don't worry about it.
Ok don't be to hard on me but for some reason I have thought you are not supposed to paint water based paints over oil? I remember in my earliest days of sign making (5 years ago) I would try to coat out MDO boards with latex paints. I could never achieve a perfectly smooth finish. The MDO boards we get here are already finished with a white enamel. I would lightly sand the boards and roller coat them with latex. The finish was always marked with fish eyes no matter how many times I combed it out. I think I went to my local hardware store at the time with my problem and they told me never to paint water based over oil? Is this not true? When I was told I took it as a general rule. The reason I ask is on the redwood signs you mentioned you use an oil based primer and than coat out with latex. Was I misinformed back then or is the oil based primer formulated differently so it will accept water based paints? Sorry for the remedial questions but if I don’t ask I wont know.
The tannin in the wood is water soluble and will bleed through an almost infinite number of layers of water based paint and leave a darkened stain on your finish. For me, it has only been a problem on light colored areas. If painting a dark background, it is not noticeable.
Water based Kilz won't stop it. I have also had it come through shellac, which surprised me. Oil based primers stop it well.
You can also do all your finishing with oil or solvent based paints and you will not have a tannin bleed problem, however I prefer the 100% acrylic paints. The acrylic paints such as Sherwin-Williams Superpaint seem to last longer than oil and they will also flex with the wood as it expands and contracts in changes in temperature and humidity, which helps keep the paint from flaking later. The paints adhere tenaciously to oil based primer.
I have tried all kinds of techniques in the finish first method and always have to come back and patch or mess with something to get the job right. I don't think I have ever truly saved time with that method, although I will probably try it again when some dumb brainstorm hits me on a process I haven't tried. I should have Raymond or Mike whack me upside the head if I even think of doing it again. Raymond is closer but Mike lives in a prettier area. Besides, if we end up fly fishing, I'll forget about the sign...
David M. Harding
A Sign of Excellence
Carrollton, TX www.asignx.com
No need for me, John. David and Ray cleared it all up for you.
I know the latex over oil doesn't make sense - but that's what the California Redwood Association suggests - and it has worked well on over 1,000 sandblasted or carved redwood signs we've made over the last 22 years. Latex over OneShot is a no-no - latex over oil based primers is A-OK.
Welll said by both Ray and David re: tannins (or tannic acid) in the wood. That's what makes redwood so tough against rot and bugs, John. It's the tree's natural way of protecting itself.
John - you are right. Normally, any latex paints over oil based is a failure waiting to happen and I would never recommend it. However, for some reason, the latex over oil based primers does work. That's what it says on the can, and it has been successful for us for about 25 years now.
Maybe somebody smart like Kent Smith can tell you WHY it works, but I only know that it works from experience.
We use 100% acrylic latex for almost all of our work now, including MDO. The finish is not that hard, glass-like look that you get with enamels, but it really does last a lot longer in our Texas heat.
Thank you for posting your experience using oil based primer with a top coat of latex.
The only way I have found of trapping tannan bleed through is with an Alkyd, oilbased primer or alchohol type such as Kils. Either way, Sherwin Williams recommends oil based primer for their latex paints. That has been working well for twenty years.
Chatted with Kent Smith this morning about something unrelated - but did squeeze in the question about oil primer - latex topcoat.
Answer? We're using the wrong terminology.
Latex is not latex anymore - it is waterborne ACRYLIC latex - which sticks to absolutely everything. That's why it works now - but used to be a no-no. Latex was a different formulation entirely in that it didn't use acrylic. Just advancements in the paint field.
So that is the short answer. But there is even more to know about it . . . and someone may post that here later.
Jay - thanks for the clarification. When you have the time would you write down EXACTLY what Kent said? If you are like me, I get about every third word he's saying. When he's explained the answer to my question I usually say, "Now, would you put that in language that I can understand - in one sentence." It's scary when people know that much. Kind of like talking to Rick.
Paint technology is changing rapidly - some good and some not so good. I just had some metal frames powder coated....now, there's a great process.
Just got back from jousting at windmills getting a sign permit with the county which I try to only go through once every 5 years or so since their system is so convoluted. Jay started the answer so here are a few more hints and ideas.
There is a technical difference between water based and waterborne paints of any type. The high-end primers from Chromatic, Coastal, Jay Cook et al are waterborne acrylic based and adhere well to everything except teflon and polycarbonate. In layman's terms these are not latex paints and should not be confused with the early latex protocols. Their advantage is also that because of the partical size of the resin, all paints adhere well to them and once cured, no topcoat will lift them. (one should not use acid etching primers over any other primer or finish coat) Durable topcoats also require a primer which seals the surface and has the same expansion/contraction coeficient as the base material and the topcoat. Acrylics perform well under that specification too. As for the migration of tanic acid in redwood, cedar and some hardwoods (not to mention tea) can be sealed easily by the acrylics. At Chromatic we created a formulation in primers for specifically sealing tanic acid and later just made it a part of both Ti-cote and Universal Primer. If you are still getting migration with either acrylic primer or shellac, the coating has voids in it. The same is true for plasticizer migration when coating vinyls such as banners with acrylics.
There you go, Ray!! Straight from the "horse's mouth".
If I have paint questions, I too ask Kent. As I said to him this morning, he is encyclopedic in his retention of all things 'paint'. Judi says he seems to forget the little things. Or does he???????
Every third word? Shoot, Ray, I get every other word. Mostly because I am frantically writing down what he says!!! It must be that Texas heat cooking yer' brain!!
John ,
Good Post here, I done many both ways and usually find that when doing the finish first method if the sign is blasted a little to close to the surface, we see the mask burn a little and these signs tend to have a few chips around the edges of panels. For many years we choose to use First Step with 2 coats spread over 2 days, then mask to blast. As Mike said, it tends to speed up the finishing time.
If you want to have better success with the finish first method, I suggest that you use a med-low tack blast mask, then before applying the mask, spray the surface with a heavy amount of rubber cement, this method should assist in preventing the edges from peeling off.
Kent, we tend to stay away from latex and go with oil, oil, oil.
So if it'll stick to anything, will the acrylic latex enamel stick to a car well enough for pinstriping as well?
Ron,
I don't believe I suggested the "Finish First Method" speeds up finishing time. On the contrary, I think it is much, much slower if you add up all the steps and drying time.
Mike Jackson
Mike Jackson / co-administrator Golden Era Studios
Vintage Ornamental Clip art
Jackson Hole, WY
Ron, it depends. There are many other surfaces that one would not expect a waterborne PRIMER to adhere such as stainless steel, silicone glass, waxed wood stains, some powder coats and two component urehtane acrylic car finish. Over automotive acrylic, lacquer and alkyd, the acrylics will adhere. And just to be clear, not common latex.
I too am just starting to blast cedar signs along with a few other related projects with glass and granite and marble. I think this post just about answered all my questions I could ever have had on the subject. In fact a few of the problems that I have already had were covered in this topic. I thank everyone here for your post as well as this will save me a lot of heart ache in my new venture into the world of blasted signage...and keep my feet dry.
Denver Chapter of the Letterheads