Hull Planking Question

[glbarlow]

Quite the dissertation. It is my opinion that your ‘facts’ are just another opinion and like all opinions, including mine, worth about as much as that toilet paper roll - though everyone knows it should hang down from the front. 
 

Anyway, I use CA and I’m happy doing it. This post has gone off the rails.  I’m out. 😇

Edited December 27, 2020 by glbarlow

[Bob Cleek]

5 hours ago, glbarlow said:

Anyway, I use CA and I’m happy doing it. This post has gone off the rails.  I’m out. 😇

 

Well it was fun while it lasted. Not to worry about "dissertations." I was once a cable teletype operator and still type about as fast as I can talk. That and the fact that my fingers aren't cemented together!  

[Roger Pellett]

To add to the discussion.

 

 I have been using CA glue for assembling the model soldiers that I have been painting.  I use very little on the end of a toothpick or something smaller.  If I use much more, my body tells me so-  A nasty sore throat and blocked sinuses.  If I tried to use it in any quantity I’d have a severe allergic reaction.  To me, whatever limitations PVA glues have are nothing compared to CA.

 

My house here in Duluth was new in 1990 and built to my specifications.  We have gas forced air heat and air conditioning.  Neverless, we have significant humidity swings.  Very low in winter and higher in summer as Duluth summers do not require AC most of the time.

 

My models range in age from new to 45 years old, were built with PVA glues and have held up well

 

 

 

Edited December 27, 2020 by Roger Pellett

[Dr PR]

Bob,

 

I appreciate the information you are providing, although I wonder if some of your "facts" aren't just "opinions." Please don't take that as a criticism - I am skeptical of most things most people say! There are a lot of "alternate facts" these days!

 

Can you recommend a good source of information about woods and shrinkage/swelling with humidity and temperature changes? I have seen some numbers for the coefficient of thermal expansion of woods, but nothing on humidity effects.

 

You gave an example wood swelling 1% with humidity. That seems pretty extreme to me. If my house (made of wood before plywood was used) swelled 1% it would increase in height about an inch and more than 4 inches in length! Of course it does expand and contract some, causing an occasional door to be hard to close, but my guess is it less than 0.1%, otherwise a lot of things would buckle. I stress the word "guess" because I have no way to conduct an experiment to measure expansion/contraction of the house accurately.

 

Also, almost all of the boards are cut with the grain running lengthwise, including joists, wall studs, rafters and side planking, so I guess it would expand less lengthwise to the grain than crosswise to the grain.

[Rik Thistle]

Roger,

 

We have gas forced air heat

 

When I was younger the family home had the same. It meant, in winter, the house was full of very dry air which was not good for the sinuses etc.

 

I suspect the forced air heat dries out the air.

 

Richard

[Jaager]

1 hour ago, Dr PR said:

Can you recommend a good source of information about woods and shrinkage/swelling with humidity and temperature changes? I have seen some numbers for the coefficient of thermal expansion of woods, but nothing on humidity effects.

You could check The Wood Database.  The factor that is pertinent is: shrinkage.   Ambient air changes in moisture content are probably only a small fraction of what the moisture concentration would need to be to match what green wood would have to be.  For the most part, change in length is too small to be significant.  A house framing involves intermittent timbers with nothing to push against. Any plywood or OSB sheathing has any length or width changes subject to being cancelled out because of the alternate orientation of layers.  The thickness does probably change with the environment.

 

As for planking in a model, I am thinking that planking size changes would be subject to some restraint if any tangential increase due to increased moisture was met by a resistance force that was greater than the force that internal water can exert.  Side by side planks pushing against each other may keep a limit on how much water could enter.  It may not move as a unit.  In POF, the frames that the planks are bonded to  are longitudinal to the direction that the planks "want" to move.  This would resist any movement.  Edge glue between planks may be subject to being squeezing, but a tight bond would have very little glue to be squeezed.  

 

It was a material used well before my time, but would hot pot hide glue not be an even more archival favorable bonding material than even PVA?  I suspect that it is way more trouble to use than any advantages it would offer.  It is easily reversible by exposing the bond to hot ethanol.  The protein that forms the bond is it not dissolved.  It is completely denatured, forming small balls that are easily removed.

 

I consider CA to be a completely no go material because along with its chemically toxic vapor, questionable half life, and weakness at resisting sheer forces - in my very limited experience with it,  I found that once opened, a bottle quickly dried out.

 

I am also somewhat dismayed by the apparent popularity and enthusiasm for wipe-on poly.  To my eye, it is too plastic looking as well as tending to produce a layer that is too thick.

Edited December 28, 2020 by Jaager

[Bob Cleek]

2 hours ago, Dr PR said:

Bob,

 

I appreciate the information you are providing, although I wonder if some of your "facts" aren't just "opinions." Please don't take that as a criticism - I am skeptical of most things most people say! There are a lot of "alternate facts" these days!

 

Can you recommend a good source of information about woods and shrinkage/swelling with humidity and temperature changes? I have seen some numbers for the coefficient of thermal expansion of woods, but nothing on humidity effects.

 

You gave an example wood swelling 1% with humidity. That seems pretty extreme to me. If my house (made of wood before plywood was used) swelled 1% it would increase in height about an inch and more than 4 inches in length! Of course it does expand and contract some, causing an occasional door to be hard to close, but my guess is it less than 0.1%, otherwise a lot of things would buckle. I stress the word "guess" because I have no way to conduct an experiment to measure expansion/contraction of the house accurately.

 

Also, almost all of the boards are cut with the grain running lengthwise, including joists, wall studs, rafters and side planking, so I guess it would expand less lengthwise to the grain than crosswise to the grain.

 

If I state something that sounds like a fact, like the percentage of wood movement, you can take it to the bank. I don't write stuff like that without checking with authoritative sources. Anything else is an opinion. 

 

As mentioned, The Wood Database on line is very complete and useful. See: https://www.wood-database.com/wood-articles/dimensional-shrinkage/  The federal government's publications are very helpful. You will find just about anything you want in the out-of-print and highly collectable (an hence expensive) Wood: A Manual for Its Use as a Shipbuilding Material, by the US Navy Bureau of Ships and the US Forest Products Laboratory  (1945) Fortunately, it's now available for free on line.  https://books.google.com/booksid=4LosAQAAMAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false Also How Wood Shrinks and Swells by the US Forest Products Laboratory contains an extensive spread sheet of the shrinkage factors of every wood under the sun. https://www.fpl.fs.fed.us/documnts/pdf1957/peck57a.pdf

 

The Workshop Companion has a lot of quickly accessible information: http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/2_Wood_Movement/2_Wood_Movement.htm

 

Note that the Workshop Companion offers a rule of thumb that if a board shows mostly flat grain on its face, you should allow for 1/4" total wood movement for every 12 inches across the grain, which "will accommodate an annual change of 8 percent moisture content, much more than is common in most areas."

 

How much your house changes shape with changes in humidity is a function of many factors, primarily depending upon the species of wood, its grain orientation when milled, and the direction in which it is oriented in the construction matrix. The articles above will explain it all in greater detail. You are absolutely correct, though, that one of the primary observable symptoms of wood movement in a house is the doors sticking in the summer when the humidity tends to be higher. 

Edited December 28, 2020 by Bob Cleek

[Bob Cleek]

1 hour ago, Jaager said:

It was a material used well before my time, but would hot pot hide glue not be an even more archival favorable bonding material than even PVA?  I suspect that it is way more trouble to use than any advantages it would offer.  It is easily reversible by exposing the bond to hot ethanol.  The protein that forms the bond is it not dissolved.  It is completely denatured, forming small balls that are easily removed.

 

I consider CA to be a completely no go material because along with its chemically toxic vapor, questionable half life, and weakness at resisting sheer forces - in my very limited experience with it,  I found that once opened, a bottle quickly dried out.

 

I am also somewhat dismayed by the apparent popularity and enthusiasm for wipe-on poly.  To my eye, it is too plastic looking as well as tending to produce a layer that is too thick.

 

Yes, old fashioned hide glue is a great adhesive, but it does demand clamping and it has to be mixed and kept heated in a glue pot. It doesn't have any shelf life once it's mixed, as far as I know. I'm told it's aroma is highly disagreeable, as well. It's the gold standard for fine furniture builders and restorers, though. Interestingly, Titebond has invented what they claim is a true hide glue in premixed liquid form that does not require heating. The next time I have to pick up some glue, I plan to try it. http://www.titebond.com/product/glues/9e9995b4-08eb-4fc6-8254-c47daa20f8ed

 

I agree completely with your conclusions regarding CA. Its shelf life can be extended if you store it in the freezer when not in use, though. I do keep some on hand for repairing broken ceramics and such, but not for model building at all. 

 

Agreed with respect to wipe-on poly, too. This may be an "opinion," but, even applied very thinly, there's no way to overcome the "plastic" look of the stuff, to my eye, at least. Perhaps that can be improved by fine sanding it out, but there's nothing I know that will duplicate the finish of real oil-based paint, varnish, or shellac that's been properly applied and, if desired, hand-rubbed with rottenstone and pumice. I don't think a lot of people have had the pleasure of running their fingertips over a hand-rubbed finish these days. 

 

(PS: In reading Titebond's product literature, it appears that use of water-based paints over hide glue may be inadvisable. See: http://www.titebond.com/App_Static/literature/glues/Crackling.pdf)

Edited December 28, 2020 by Bob Cleek

[Charles Green]

Bob:

 

The bad odor from hide glue occurs when a pot of glue is left to set for a few days, unused, until it turns rancid.  Discard unused glue when done with a glue up and there will be no problem.  The glue comes in a dried granular form that is mixed with water and heated just prior to use.  The dry granules are odorless.   

 

 I am involved in making a display case for a Native American artifact; a wooden, Tlingit halibut hook, and this raised concern about the archival properties of glues, finishes and types of wood.  All common "wood glues" off-gas ascetic acid as do finishes based on organic oils or waxes.  This off-gassing persists at ever diminishing levels for years and can accumulate to deleterious levels in the confines of a display case.   I've been unable to find data on the archival suitability of CA.  When it "kicks over" it does emit a puff of very disagreeable gas.  Again, I don't know the chemical nature of this gas or its longevity.  Nor are the archival properties of Titebond's liquid hide glue to be found.   What my research boiled down to is traditional hide glue and shellac are the only common glue and finish that do not pose any archival threat.  These are what I will use but I still worked unobtrusive ventilation holes into the case's design.         

[Jaager]

7 hours ago, Bob Cleek said:

Titebond has invented what they claim is a true hide glue in premixed liquid form that does not require heating.

Bob,

I remember reading a negative review of the Franklin (Titebond) Liquid Hide Glue here.  A different product Old Brown Glue got higher marks.  A problem with a premixed hide glue is the relatively high water concentration.  I used the Franklin product as a temporary bonding agent, but it did not do what I wished.  It was mostly because of the way I applied it.  I was too through with the application.  It held too well.  Spot application probably would have held. I totally covered both surfaces with a thin layer - the same as I do with PVA.  A wicking spacer of newspaper to allow the ethanol debonder to penetrate the frame thickness probably would have helped. 

 

Charles,

Hot hide glue is probably the wise choice for an archival case.  

 

PVA is very acidic.  I think it is a strong acetic acid solution.  The acid concentration is higher in the water resistant bond product.  It is high still in the waterproof bond product. 

The agent forming the bond is poly vinyl acetate.  When the polymer bond forms, acetic acid is released. As the water evaporates, liquid acetic acid is left behind.  It has a degree of volatility at room temp, it is just much less than water.  The polymerization reaction probably continues over time - possibly years.  That is probably part of the source of its continuous outgassing of acetic acid.  I think this means that the bond gets marginally stronger over time but it also probably becomes more rigid as the degree of crosslinking increases.   This means that a properly made ship model case needs adequate ventilation to evacuate the acetic acid gas as well keeping it from becoming an oven.  It also means that castings with any lead content are doomed with a PVA bonded model.

[Bob Cleek]

2 hours ago, Jaager said:

I remember reading a negative review of the Franklin (Titebond) Liquid Hide Glue here.  A different product Old Brown Glue got higher marks.  A problem with a premixed hide glue is the relatively high water concentration.  I used the Franklin product as a temporary bonding agent, but it did not do what I wished.  It was mostly because of the way I applied it.  I was too through with the application.  It held too well.  Spot application probably would have held. I totally covered both surfaces with a thin layer - the same as I do with PVA.  A wicking spacer of newspaper to allow the ethanol debonder to penetrate the frame thickness probably would have helped. 

Thanks for the tip! I'll pass on the premixed hide glue.

 

Strongly agree on the drawbacks of PVA adhesives acidity, as does the National Park Service in their conservation standards. (See: https://www.nps.gov/museum/publications/conserveogram/18-02.pdf )  I've repaired "lead bloom" issues by providing case ventilation and it seems to have worked, for the last 20 years or so, at least. At present, short of real hide glue, PVA adhesive seems to be a necessary evil. I expect minimizing PVA to small amounts used in model construction serves to minimize the problem. For that reason, I use clear shellac for stiffening lines and sail material, not thinned PVA adhesive. Case ventilation is essential and not just for lead oxidation prevention. The acid from whatever source slowly deteriorates everything, particularly fiber rigging and sail material.

 

While on the subject of acidic outgassing and display cases,  based on the professional literature, I only use UV-sheilding picture frame glass for display cases and avoid all plastics in case construction at all costs due to their potential acidic outgassing characteristics. High quality plastic glazing materials (e.g. Perspex, Plexiglas, Lucite) are reportedly inert, but I'm not taking any chances that what I'm getting is "the good stuff." (Besides, as a matter of taste, I prefer the more traditional look of a wooden or metal framed glass case.) (See: https://www.nps.gov/museum/publications/conserveogram/08-05.pdf ; See also: https://ccaha.org/resources/selecting-materials-storage-and-display )

Edited December 28, 2020 by Bob Cleek

[bartley]

On 12/29/2020 at 5:06 AM, Jaager said:

PVA is very acidic.  I think it is a strong acetic acid solution.  The acid concentration is higher in the water resistant bond product.  It is high still in the waterproof bond product. 

The agent forming the bond is poly vinyl acetate.  When the polymer bond forms, acetic acid is released. As the water evaporates, liquid acetic acid is left behind.  It has a degree of volatility at room temp, it is just much less than water.  The polymerization reaction probably continues over time - possibly years.  That is probably part of the source of its continuous outgassing of acetic acid.  I think this means that the bond gets marginally stronger over time but it also probably becomes more rigid as the degree of crosslinking increases.   This means that a properly made ship model case needs adequate ventilation to evacuate the acetic acid gas as well keeping it from becoming an oven.  It also means that castings with any lead content are doomed with a PVA bonded model.

 

Jaager,  some of  your facts here are a little misleading.

 

1. Not all PVA preparations are acidic. There are many different formulations.  Titebond has a pH around 2.6 but craft PVA and Bookbinder's PVA are neutral (pH7).  The flip side of this is that the tack time is much longer with neutral preparations so they need clamping.  The tack time for Titebond is only about 2 min.

 

2. When vinyl acetate polymerizes to poly vinyl acetate no acetic acid is released ( it is the vinyl group which reacts) but if the  product is acidic then that catalyses hydrolysis of the acetate side chain to form acetic acid and this process can continue for years.  Bookbinder's PVA is considered archival because the neutral pH slows the hydrolyses markedly although probably does not prevent it altogether.

 

3.  Polymerization, as you say, does continue slowly for some time but it is not that processes that releases the acetic acid.

 

John

Edited December 30, 2020 by bartley
spelling

[Charles Green]

Bob:

Tru Vue sells a wide range of archival glass and acrylics for framing and case makers.  Their acrylic product under the name of "Optimum" has all the advantages of glass without the weight or shattering hazard.  It is expensive.

Edited December 29, 2020 by Charles Green
Spelling Correction

[Larry Cowden]

On 12/24/2020 at 5:23 AM, Bob Cleek said:

One should carefully consider the downside risks of gluing planking seams, whether by application of adhesive to the seams, or by coating the inside of a hull with epoxy resin adhesive which soaks into the seams from inside. As noted correctly, wood moves with changes in the ambient humidity levels of the environment it's in. This movement is primarily across the grain and its amount varies depending upon the wood species and, within the same species, even the location where the wood is grown. This is called tangential movement. Most woods will shrink tangentially six to ten percent when dried and will swell back depending upon the moisture content absorbed. The amount of movement is relatively small, assuming properly dried wood being used to begin with, but can still be considerable if the distance you are dealing with is relatively large. 

 

So, if you are building a model using vertical grain stock, as one should, the tangential (cross grain) side of its planked hull can easily total six inches. That's six inches of grain to shrink tangentially and even at a rate of movement of one percent, you are getting close to a sixteenth of an inch, which would be a quite noticeable crack in a model's topsides. If the planks are not fastened to each other, each will shrink individually and if you have maybe 24 1/4" planks, that shrinkage will only amount to 1/24th of a sixteenth of an inch. (You can do the math to get an exact fraction... a good example of the advantages of metric measurements!) That amount of movement isn't going to be noticeable at all and most coatings will allow for such movement without cracking at the seams. However, if the seams are all glued together, they all move as one, and the "weakest link law" takes over. In that case, a sixteenth of an inch crack along the weakest glued seam... or a crack in the wood itself... is going to occur at the weakest point. Conversely, swelling will push the glued sheet of planking for that sixteenth of an inch against everything it butts up against, again potentially causing a structural failure at the weakest point, or tend to buckle the "planking sheet" outward, breaking the glue bonds... or the wood... at the frames. 

 

Now, with prime wood species which have low movement factors and with relatively stable humidity, you may not run into any problems at all, but theoretically, the potential is there and I've seen its results in more than one model I've restored. More often than not, parts, cap rails, for example, start popping off and nobody knows why.

 

Monocoque wood hull construction is tricky. For my money, I prefer to give the wood as much opportunity to move on its own as possible without concentrating swelling and shrinking stresses within the structure.

 

Others' mileage may vary, of course.

 

I have seen some models that used wood pins to nail on the planking. And some I have seen used brass nails. What is your experience or observations regarding these two methods and wood movement?  Also the use of a flexible epoxy such as I use on fishing rods would seem to eliminate the problems of a hard set liquid epoxy. 

[Larry Cowden]

On 12/26/2020 at 10:53 PM, glbarlow said:

Just so someone says it, a few of you need to add “in your opinion” to some of your bold unbending statements.

So in my opinion: 1.CA is the best choice for planking a hull using Chuck’s method linked above, PVA is just so unnecessary. 2. I have models over 25 years old done with CA that are just fine and look great. 3. I don’t think any well built ship model survives dropping to the floor, it’s best not to do that. 3. Edge gluing is not only totally unnecessary it’s also detrimental to the look of the hull. 4. I doubt the humidity variance in most first world homes creates an issue. 5. I’ll put up my nine models as examples of using CA for hulls any time. 
 

I don’t understand why people don’t just acknowledge design and build preferences as just that, a preference.  There are many ways that are right and many that work just fine. There are very few that are wrong, using CA for hull planking is not one of those. Why denigrate a method different than your preference, why not instead offer your method as one of many options.  In my opinion...

I would offer this up based on personal experience. I would have to disagree with your statement on humidity affects in 1 world homes. Our cabin here in the Catskills built in 2016 when we moved in experienced major humidity problems due to lack of sufficient humidity to stabilize the logs and pine T&G flooring. Checks up to 1/2" wide opened up in logs and beams. Flooring shrank tangentially opening up cracks. Only the addition of a humidifier to our central air system has stabilized the cabin. The cracking and popping of logs and timbers has significantly been reduced. Wooden ships in 9% humidity would certainly fair the same. We run a minimum 40% humidity level year round. I see less movement when a wooden plank has need completely sealed all four sides.

[glbarlow]

I'm not sure I was factoring a log cabin into first world homes - the variance in most HVAC systems keeps the humidity within a range that it would not affect CA glue. I was not intending to get into a home construction dialog, but I'll withdraw the general point and just say specifically that the humidity range in my home does not affect the models I've build using CA glue and let it go at that.

[No Idea]

You know..... we built lovely model ships and conversations like this make me wonder why people join forums  - They must read this and think I’m not getting involved in that.  I wonder how long my forum ban is going to be for that then  

[Bob Cleek]

6 hours ago, Larry Cowden said:

I have seen some models that used wood pins to nail on the planking. And some I have seen used brass nails. What is your experience or observations regarding these two methods and wood movement?  Also the use of a flexible epoxy such as I use on fishing rods would seem to eliminate the problems of a hard set liquid epoxy. 

 

Mechanical fastenings such as treenails and nails permit each plank to shrink and swell independently of the others, thereby spreading the wood movement proportionally over the entire structure, piece by piece, so long as the plank seams are not glued one to the other. When the seams are glued, the shrinkage (and swelling) of the solid glued piece will occur at the weakest point, often resulting in a split piece of wood or a cracked seam the width of the movement. Remember the percentage of movement, whatever it may be, is across the moving dimension of the piece. The larger the piece, the greater the movement across the moving dimension. If you glue a bunch pieces together, they will move as one. Instead of tiny bits of movement between each piece, you'll get the total movement of the glued pieces at one spot.

 

Flexible adhesives certainly mitigate the problem of wood movement to the extent they flex, but flexible joints may pose other structural problems in a model. The problem with any adhesive, including the epoxies, the limitations of their archival and working qualities.  These involve the degree of long-term changes in coloration, brittleness, acidic outgassing, loss of strength, particularly shear strength, and the reversibility of the bond in the event future conservation or restoration work may be required. These considerations usually vary greatly, depending upon the formulation of the particular adhesive. At present, the "gold standard" museum conservation epoxy adhesive is a product known as HXTAL NYL-1 designed specifically for the repair of glass and ceramic artifacts. It closely mimics the refractive index of glass and so produces an invisible repair.  It's claimed to be the only epoxy adhesive which does not yellow upon exposure to light. This is a very specialized (and expensive) epoxy adhesive having very exacting mixing and application requirements and, importantly, is not easily reversible, as far as i know. While it is an excellent product for glass and ceramic repair, it isn't very suitable for modeling because it has a very long minimum setting times in excess of three days! See: https://www.hxtal.com/ and http://www.lakesidepottery.com/HTML Text/Tips/Hxtal-NYL-instructions-glass-epoxy.htm

 

 

Edited January 2, 2021 by Bob Cleek

[Dr PR]

This thread has yielded some very good information!

 

Some of the more detailed and esoteric points really apply if you intend to create a museum quality model. For this you should read the requirements for models from the Smithsonian, the US Naval Academy Museum, etc. For archival purposes we can forget epoxy, CA, and many other glues. The wood pieces should be cut to minimize shrinkage, etc. Forget plastics, 3D printing, pot metal castings and other materials that have not withstood the test of time. And so on ...

 

But most of us are not building museum quality models (we wish!). We are building for the fun of it and the satisfaction of having done our best. It looks like the majority of builds are from kits and we use whatever materials are supplied. I seriously doubt most kit makers carefully cut each piece the "right" way! When we do make modifications to the kits or kitbash we usually get our materials from a local hobby shop, or maybe order online. Again you get whatever the supplier sends. Frankly, as careful as I am about trying to get things "right" on kit builds, I really don't think my models should last forever!

 

I think the worry about wood expansion is perhaps a bit exaggerated. It is a problem in buildings with no humidity control that are constructed of large diameter wooden beams. Cracks are common because of stresses accumulated over large dimensions. Even on my house I have seen cracks open between siding boards, about 1/8 inch in 8 feet (96 inches) or 0.0013%, when summer temperatures get up to >100F for several days and humidity drops below 20%.

 

But our models are made up of pieces of very small dimensions so very large stresses don't accumulate. I looked at The Wood Database and found that some green woods do contract 8% to 12% tangentially when they are dried. However it states that after drying dimensional changes are small, typically about 0.1%. Given that number, six inches of planking would change by 0.006 inches (0.00023 mm). That is about the thickness of two sheets of #24 printer paper. I have seen cracks appear in hulls I have made where planks were nailed or glued to bulkheads with a light coat of lacquer on the exterior. However, as Bob said, this cracking is likely due to poor planking techniques as much as anything else. These were some of my first kit builds.

 

I think for most of us any materials, glues, and methods that get the job done to our satisfaction will be good enough. And everyone has their own opinions about what is "good enough."

Edited January 2, 2021 by Dr PR

[Bob Cleek]

9 hours ago, Dr PR said:

And everyone has their own opinions about what is "good enough."

 

Fortunately, you don't have to worry about a model ship sinking if you didn't do a proper job of building it.  

 

Most all of us build models for fun. Some are interested in building to the highest archival standards possible, as an exercise in discipline and technique in pursuit of a "personal best," if nothing else. Others not so much. For some, learning about "best archival practices" is more of an academic exercise than anything else. All I can say for myself is that if I were a kit builder and was spending into the four figures on a kit that I expected to take three years to complete, I wouldn't be spending that much money and time on something that I considered to be just "good enough." Your mileage may vary, I suppose. 

 

It bears noting, however, that the hobby in Eastern Europe where ship models are entered in judged competitions, is considered more a competitive sport than a hobby and consequently what they consider "good enough" is from all appearances a whole lot better than what we consider "good enough." If they'd been as good at building rocket ships as they are at ship modeling, the Russians would have landed a man on the moon long before we did! At the end of the day, isn't the exercise of ship modeling all about the pursuit of perfection rather than just one's own opinion of what's  "good enough? "

[Larry Cowden]

17 hours ago, Bob Cleek said:

 

Mechanical fastenings such as treenails and nails permit each plank to shrink and swell independently of the others, thereby spreading the wood movement proportionally over the entire structure, piece by piece, so long as the plank seams are not glued one to the other. When the seams are glued, the shrinkage (and swelling) of the solid glued piece will occur at the weakest point, often resulting in a split piece of wood or a cracked seam the width of the movement. Remember the percentage of movement, whatever it may be, is across the moving dimension of the piece. The larger the piece, the greater the movement across the moving dimension. If you glue a bunch pieces together, they will move as one. Instead of tiny bits of movement between each piece, you'll get the total movement of the glued pieces at one spot.

 

Flexible adhesives certainly mitigate the problem of wood movement to the extent they flex, but flexible joints may pose other structural problems in a model. The problem with any adhesive, including the epoxies, the limitations of their archival and working qualities.  These involve the degree of long-term changes in coloration, brittleness, acidic outgassing, loss of strength, particularly shear strength, and the reversibility of the bond in the event future conservation or restoration work may be required. These considerations usually vary greatly, depending upon the formulation of the particular adhesive. At present, the "gold standard" museum conservation epoxy adhesive is a product known as HXTAL NYL-1 designed specifically for the repair of glass and ceramic artifacts. It closely mimics the refractive index of glass and so produces an invisible repair.  It's claimed to be the only epoxy adhesive which does not yellow upon exposure to light. This is a very specialized (and expensive) epoxy adhesive having very exacting mixing and application requirements and, importantly, is not easily reversible, as far as i know. While it is an excellent product for glass and ceramic repair, it isn't very suitable for modeling because it has a very long minimum setting times in excess of three days! See: https://www.hxtal.com/ and http://www.lakesidepottery.com/HTML Text/Tips/Hxtal-NYL-instructions-glass-epoxy.htm

 

 

Do you tree nail or pin your planking as a standard rule for building?

[allanyed]

Larry,

Yes, I treenail IF I can do it at scale and it is appropriate for the vessel.   What ship, scale, year, are you considering?  If trennals are appropriate for the vessel and era, it comes down to scale for many, if not most builders.  Some ships had bolts, depending on era, nation, etc. in place of or in addition to trennals on some planks.  Assume the largest wooden trennals found on the  largest ship are 2" diameter for the hull planking.   At 1/48, the diameter would be 0.04", quite easy to make with a good quality draw plate and bamboo, boxwood, pear and a few other species.  At 1/64 you would still be at about 0.03" diameter and not difficult to make with a good quality drawplate and bamboo.  At 1:96, you would be down to 0.02, about the equivalent of a #75 drill diameter.  (Species other than bamboo, only based on my own personal experience , have not done very well at the smallest sizes. More waste in material and time than is worth it.)  For smaller ships the trennals may be smaller, say 1.5" diameter, depending on the width of the planks themselves.   For 1:96 scale I know of no draw plate that goes small enough or wood that would work.  The smallest hole on a Byrnes plate is 0.16 so too large.  28 gage wire could be used, but the ends would need to be filed and colored in some manner to replicate wood without staining the planking.  Copper wire and liver of sulfate could be used, but it will be black and not replicate wood. It does great to simulate bolts  Also care must be taken to remove metal particles that imbed in the wood as these particles will discolor as well as the intended bolt.

 

Going to deck planking, the trennals are smaller in diameter, closer to 1".   These can still be shown with some precision at 1:48, but for smaller scales will be very difficult to execute at the proper sizes.   Some use pencil point marks but these are not always consistent.  Many deck trennals and/or bolts were covered with wooden plugs making them virtually impossible to see at our scales.

 

Alternatively for both hull and deck planking you can drill the proper size hole and fill them in with wood filler or a sawdust/glue mixture, then scrape and sand finish, which often looks very good.

 

There are a number of  preferences on how to execute using trennals, so you may want to try a few methods to see what works best for you.  If in doubt, it is better to forget about trennals altogether if the alternative is to go over sized.  The appearance of over scale trennals is not a good look.

 

Allan

[Bob Cleek]

1 hour ago, Larry Cowden said:

Do you tree nail or pin your planking as a standard rule for building?

 

What Allanyed said.

 

Like most, I expect, my practices have evolved over the years. Now, I always glue planks at every faying surface. I will also mechanically fasten a plank by with a wood peg or countersunk pin or piece of copper wire set in shellac or thin adhesive and puttied over, wherever I wish to ensure the greatest strength possible, such as in hood ends and every few frames along the less sharply curved length of the hull.  A  cleanly countersunk fastening hole puttied and sanded with a suitably colored putty (sometimes PVA thickened with wood flour) can easily be made invisible or appearing no differently than a wood trunnel. A brightly finished hull with visible fasteners requires the fasteners to be properly placed as in the prototype, but I need far fewer fasteners when the trunnels need not be seen, as is usually the case at most scale viewing distances.  I prefer not to rely solely on adhesives for fastening if at all possible. I never place fasteners which will be visible on a model except where they would be visible on the prototype. Where they are visible on the prototype, I take care to ensure they are properly scaled and not visually overemphasized.

 

What I almost never do is use CA for anything. What I never do is glue plank seams one to the other.

[tomsimon]

This has been an invaluable topic of discussion for me.  I wanted to send a thanks to all who were kind enough to help.