Material and Finish for outside Cross ??

[gbatten]

Perhaps some of the experienced craftsmen on this forum can give me some adivse on this unusual project.

I have been asked to build an 18 foot tall cross for a local Lutheran camp. The cross with be mounted outside and will have to endure North Carolina weather. It is part of an outdoor chapel. I am also making an altar that will have some inscriptions (that is where the Shopbot comes in).

The cross and altar are to be constructed out of wood (at least the visible parts) and are to have a natural or stained finish (not painted).

My two main concerns are:
(1) what type of wood to use
(2) how to finish the wood (for endurance)

I have some ideas but I would like to hear the advise of others before I settle on a method.

Thanks to all for input and advise.
..Gene

[srwtlc]

Gene,

Some woods that are good for outdoors would be..Western Red Cedar, Redwood, White Oak (not Red Oak!), and Teak, which is a very good outdoor wood. You could also use the brown treated lumber.

A finish something like a Tompsons Water Seal, which will have to be frequently reapplied, or I have heard of using the "clear base" of some of the quality outdoor paints. How about termite protection where it will be?

[gbatten]

Scott,

Thanks for these suggestions. Yes, the woods you mentioned are frequently used for outside applications. I may end up using one of them, but I wanted to hear what others suggested in case there was a choice that I was not considering.

I would like to keep the cost as low as possible and avoid warping, cracking, and splitting problems. Presently, I am considering a good quality plywood (not pine). By using plywood I will avoid having to make "glue ups" to get the width of about 18 inches that is proposed for the "trunk". (This is going to be a BIG cross). It will be necessary to seal the surface very well. Since my customer wants a stained wood finish, I think treated wood might not work. Around here, treated wood has a green tint so it would not look "natural".

To seal the wood against rot and weather damage, I have considered using 2 or 3 coats of oil based polyurethane.

The comment about termites is good. My customer wants to either hang this huge cross from two trees or mount it on a pedistal. In either case, termites should not be a problem.

Does anyone have any "cautions" or advise to pass along?

Thanks, ...Gene

[chamcook]

Gene,
I love varnish. The last boat I built had 12 coats of Epifanes on the interior. However I would say that 2 or 3 coats of varnish or polyurethane on any outdoor project will be a maintainance headache. Either will eventually haze then crack then peel,
I would consider one of the "breathable" varnish alternatives: Epifanes RapidCoat, Epifanes RapidClear, Sikkens Cetol, Armada. There are probably others. They will last longer (but not forever)
A traditional linseed oil/pine tar/turpentine mix, the "downeast deck formula" is easy to keep up. You just brush/wipe more on. It never peels. However it darkens dramatically with age, turning almost black which might not look all that great on your cross. It looks great inside a traditional wooden dinghy.
There really is no miracle finish that I know of. My first choice for your project would be the Cetol. If you use it be sure to put enough on.
David

[dmidkiff]

Gene,
One other wood for outdoor use would be cypress. It is light colored and rot resistant. As for a finish you could use a deck stain that comes in a few colors. The cypress will naturally grey over time. I used an exterior polyurethane on some cedar and it cracked in less than 1 year. Hope this helps.
Dave

[ron brown]

Gene,

Don't mind me, I'm raining on everyone's parade. I would select a wood from "Wood as an Engineering Material". Rot resistance, durability and physical properties are covered in the publication.

I know of no finish for "bright finished" wood that is durable. The boat David speaks of with " 12 coats of Epifanes", well, if it were exterior, and in the tropics, it would need a coat of varnish a month to stay "Bristol". I've heard all the claims, used a host of products and I'll guarantee if varnish is used in the lattitude of North Carolina, 3 to 5 coats of varnish a year is needed for things in full sun - for a presentation type finish on wood - after 10 or so base coats.

Urethanes, linear-ureathanes, poly-urethanes and other "magic finishes" last a little longer - until they finally do fail and that hard, hard to strip material has to be taken to bare wood to start over. Unfortunatly, the next "miracle" finish is usually only a little better than the last, IMO.

But, the truth won't sell a product. So, good luck.

Ron

[gerald_d]

Ron, have you ever tried the Sikkens Cetol mentioned above? It does not peel, and NO stripping is needed for a single re-coat layer every 3-5 years. It does not give a hard gloss varnish look - the appearance and feel is "waxy" with a slight "satin sheen". And yes, it does last in lots of sunlight in latitudes of less than 30 degrees. But, over here it is double the price of anything else - however, I use nothing else outside.

[elcruisr]

I can say from hard experience as a shipwright that the easiest finish to maintain is the Cetol. In more tropical lattitudes it's a coat every 6 months though. Conversion varnish might go several years but the refinishing is not fun.

As for woods, I'd avoid most plywood. Unless completely sealed the endgrain is going to give you some big headaches in a few years. Western red or eastern white cedar would do OK as would cypress. If you can deal with the weight then ipe or jatoba would be good candidates. Almost anything solid in those type of dimensions is going to give you some checking problems. If I had to approach it I might do it out of marine grade 1/4" plywood in mahogany or the like. Build it in box section, seal the inside with several coats of epoxy, wrap the outside in a coat of 4 oz finish cloth in epoxy, flood coat the epoxy over that and then shoot it with automotive clear. Any engraving or lettering could be attached as plaques. Very time consuming and expensive but it would really last.

See what happens when you drag a shipwright into it???

Eric

[beacon14]

you might try contacting manufacturers of laminated beams to see if any of them have a product which can be used outdoors. 18" wide x 18' long is nothing to them - it would certainly cut down on the labor on your part.

Good luck,
David

[rookie432]

For outdoor applications/finishes I might check out some of the automotive clears. A product I have had the opportunity to use is PELUCID. Can be brushed or sprayed and works on wood an metals. Very high solid content and crystal clear. Looks like water. Rock hard finish and has uv filters and doesn't discolor.
Drawbacks= Glossy (only a drawback if you want a satin finish)

About $155 a gallon but good stuff.

[papadaveinwy]

Gene if you still need to do this to finish the wood I would recomend a product called Flood Pro it is made by Flood and can be bought at Sherwin Williams paint stores or a Tru-Value I used it on The exterior of a Night Club Dinner Club owned by Dennis Weaver about 5 Years Ago in Ridgway Colorado at 7000 ft elevation and and very extreem conditions and it still doesnot need to be redone yet maybe in 2 or 3 more years. It needs to be Brushed on so that it pentrates. Also if I were you and if you have ever done any faux painting i would talk the Church into the alter being done to look like Marble, in a green tone. done with exterior paint and done right it would look just like the real thing. David in Wyoming

[ron brown]

Gerald, Eric, Davids, and Dave - Thanks for the updates on exterior finishes. I haven't used Cetol or Pelucid. Probably my fear and experiences with miracle finishes when I was building, rebuilding and refinishing boats keeps me from using it. I won't lie to a customer. And other, less experienced (and maybe lsss honest folks), would tell folks, "This new catilized varnish will last (insert lie here)." Needless to say, If the customer doesn't know what he is dealing with, they go places where they get promisess out of line with reality.

I think Eric's comment on epoxy encapsulation has a chance of lasting several years. I'd still paint the top surfaces, the ones never seen, with aluminum paint and then a good white paint for UV killing. I might even bond a thin piece of copper to the top surfaces in leiu of paint.

One of the problems in wood these days is the trees are a lot younger. All of the Cypress, and most other woods I have seen lately, has large amounts of "sap wood" in relationship to heartwood. "Quarter-sawn", the industry standard 100 years ago, is now a by-product of sawmills. Decisions are taken by accountants rather than by craftsmen or other professionals (like engineers) in business. Where Gene is, North Carolina, he should be able to get good "Juniper", commonly known as "Southern Yellow Cedar", although there are no cedars native to the Americas - just trees that reminded the European craftsmen of the true Cedars of the "Old World". The cost should be reasonable - or fairly reasonable considering the options.

Keeping the base off the ground will help a lot too. Protection from sun and protection from water is the goal... Have them put a roof over it.

Ron

[elcruisr]

Ron,
boy am I with you on wood quality. A little while back I had a very arrogant lumber salesman try to tell me that the quality of wood and the grades hadn't changed in 50 years. The conversation that followed wasn't pretty. The last time I did a replank job on a 60 footer I almost cried at having to use the best grade of mahogany I could find. It didn't hold a candle to the stuff I'd used to use when I started. I won't even get started on domestic hardwoods....

One thing you can still get shipped out of the gulf south would be "sinker" cypress. They are old growth logs that sank in sawmill ponds and holding areas way back when. It's rarely kiln dried but some really good stock is available. I've worked with pieces 30" wide, 20' long, clear and straight grained with a really high ring count. It's has lots more oil content and really is rot resistant unlike the new growth cypress to be had.

I also recently started working with a new import called "Lyptus". It's a genetic hybrid of mahogany and eucalyptus grown on old rubber plantations in south america. Most people think it's mahogany unless they really know their species. On the good side it's reasonably priced, rot resistant, pretty clear and consistant grain and reportedly holds finish well. It's also really dense and hard. It's downside is the silica content which makes it a little hard on cutting tools but not as bad as teak. It works great for carving on the shopbot as with the density it holds really crisp details with clean edges.

If you do epoxy coat something for exterior use it does need UV protective coating. I know what you mean about promises in the boat business, I've heard some whoppers there as well. My favorite was watching some gold plater getting ready for a run in the Carribbean. "Don't you think all that varnish is going to be a pain down there? You might want to overcoat it with paint." After the shocked look at such a suggestion it was usually followed by a haughty "That's 10 coats of XYZ varnish and it should last several years..." Usually within six months it was being redone over and over again....

Eric

[gbatten]

These are some really great suggestions! Thanks to all who have shared their experience and wisdom.

I am still considering options on this project but now I am much better informed.

Best regards, .... Gene

[simon]

for the sake of north carolina weather it might be worth considering the weight of the finished cross when converted into a missile by a tornado or whatever you get round there.
Being a paraglider pilot a have the deepest respect for weather.
Maybe a ribbed construction like the fuselage of a sopwith camel

[bleeth]

Just in case you need a few words from another old boatbuilder: Epoxy is not UV resistant and will break down unless coated with a UV inhibiting finish. To learn more about it from the best go to www.westsystem.com (http://www.westsystem.com) The advise you have been getting about sikkens cetol is spot on. The stuff is great and I have seen it last for years on Puget Sound. I would laminate my timbers for this one and would go with white oak, cypress, or western red cedar. Eastern cedar won't last the way western will.

Dave

[kerrazy]

This I am sure is way off the mark but I must add it to the mix. Sign foam will last for many years, and when acrylic latex is applied you have a good 10 to 15 years of never touching it. This can not be said for any other application. any other method, you will have to deal with moisture wanting to escape from the wood, which will cause oil or solvent based products to bubble or crack. solvent based products as you may no increase their hardness year after year where acrylic paints have more elasticity and will move as the substrate expands and contracts. I would create a carved faux grain pattern on sign foam and then paint it to resemble grain as well. Deepending on the thickness of the the cross you could sadwich plywood in between the signfoam to aid in rigidity.
This will give your customer a product that will not warp, crack , peel or blister and when all said and done will reduce maintance cost of the sign. Latex acrylics will not fail from UV as will solvent based products either, so any touch ups can simply be made with out have to try and match faded grain colours.

Food for thought.
Dale

[rfitzgerald1@nc.rr.com]

Gene Batten - I live here in Raleigh, NC and have owned four ShopBots. I also have a degree in Wood Science & Technology from N.C. State University. I routinely fabricate outdoor items like signs, patio bars, boat parts and custom millwork for use around Wilmington, Morehead City and the Outer Banks. The advice folks gave above is accurate; however, let's get back to your intended questions (1) Wood species Selection and (2) Finish system selection. That's easy. (1) Nearly any species as long as it is protected from direct weather exposure! (2) West Sytem Epoxy, Cetol or Sikens! Yes, I am being funny but only to a certain extent. What is the plan for long term maintainence? Who will do it and how often? What is the maintainence budget? Are you offering a guarantee? If so how long and how specific? Do you have fabrication limitations to consider? How about allergies to wood dust (i.e. are you allergic to silica-laden woods like Mahogany, oils in Teak, Cypress, etc.? What about a budget? Would the Lutheran church be open to synthetics as long as it resembled wood? How will you permantly mount the Cross and Alter? These are just a few questions I would ask before selecting a wood species and finish system. I am not trying to make this more difficult but to me the Cross is the biggest issue. I assume it will not be protected and thus species selection design and maintainence are all equally important questions. During the filming of "The Passion" the lead actor was struck by lightining. He was lucky. In today's litigeous society I cringe at the thought of lightining striking a parissioner via the Cross or the Cross falls on someone and wow! Dewy Cheatum & Howe will be all over you like stink on ....! My suggestion is to anchor in a flagpole encapsulated by foam. Cap the horrizontal surfaces with lead/aluminum/copper to protect from hail and acid rain. I've built synthetic looking timbers like this for resturants. You can paint in the wood grain look or carve with ShopBot or with hand held Rotary Tool. Call Southeastern Sign Supply here in Apex and they will sell you both the sign foam, adhesives and the correct finishing system. (Beware - sign foam is expensive but remember you can leave the foam 1/2" thick and make a box construction that fits like a sleeve over the flagpole). The foam carves beautifully so you can inscript the Cross as well! If money is really tight then use Gorilla glue to laminate two treated 2 x 12's and bolt on the horrizontal members. Again, with wood you must encapsulate with a resin, vinyl or that new lifetime polymer now available but that is for another discussion. You could use laminated timbers. It would be easy to fabricate a Cross but you'd need rigging or a small army to raise it! I'm building an exterior porch in downtown Raleigh (Boylan Heights/South Street) in which I used CCA treated laminated timbers. These things are massively heavy. Call my buddy Glen Baker in Wilmington at LP and he will advise you on the pros and cons of using laminated pine for your application. He is the assistant plant manager (or senior production engineer - I forget).
Regarding the Altar, species selection criteria becomes much more flexible if you can use a cement slab (or marble/slate/metal) to overhang the base by a considerable amount. If you have a 2' overhang I would even consider marine plywood to facilitate ShopBot carving and such. I would use Roman capped cement collums at the four corners to minimize the appearance of the overhang. Finishing wood with Cetol would be fine in this scenario.
I hope you find value in my suggestions. Call me if you wish to discuss this or if you wish to tell me I'm an idiot. Either way you'll feel better! Best Regards! Robert Fitzgerald