Fibreglass to hide planks?

[puckotred]

Hi all,

I'm struggling with the hull of "Bohuslän". Planked model but the original is metal. Have sanded and used filler 5 times over and still the planks are visible.

My question: Will glass fiber cloth and resin hide the planking?

[src]

Mr Pucko, I took a quick look at your build, how about a sandable primer? Something like an autobody primer, spray a good coat on sand and reapply a lighter coat. you could use an auto body filler for any minor blemishes

sam

[reklein]

Filling the grain on the fiber glass and sanding that back will be far more difficult than working the wood. Get some good light wood filler and work that down and use the good auto primer. Bill

[Shiptek]

FWIW, I agree, I've worked with fiberglass in the past and it's not great for detailed applications. The fibers are actually quite long and large, you can use finer material but it would probably get messy. Anyhow, by the time you get a layer of resin mixed and applied thick enough to hide the fibers you will end up with a 2-4mm thick coat. I would like to see what you end up doing if you end up using wood filler.

[Piet]

Hello Mr. Pucko,

 

When building my father's submarine model, the O19, to a scale of 1:50, the hull is basically made from wood and the sides and deck are planked.  After sanding the wooden planking smooth I had to use very little wood filler and then I used a VERY thin Dacron fabric, slightly heavier then a woman's hose, with resin.  A second coat of resin was applied which did not appreciably added thickness to the finished hull.  A light sanding was done to look for any unevenness and then I did use some automotive body filler to smooth out the few imperfections.

 

To finish the hull and simulate the steel hull plating I used regular file folder cardboard and glued them on in the pattern as shown on the original photos of the boot.

I opted for the cardboard instead of either copper or brass "stick-on" foil for economic reasons.  

 

In one of my careers as aircraft mechanic I am very familiar with fibre glass work and indeed the cloth used is way too heavy for model work.  The cloth I used was bought in a fabric shop and worked out just great. The added thickness, including the cardboard plating was less then 0.3 mm, which was for my scale acceptable.  If I had the money I would have used the stick-on foil though.  However, my model had to be painted and then the expensive foil would be a waste of money.  It would reduce the added thickness though.

 

If interested you can look at my method by clicking on the O19 build log in my signature below.

 

Cheers,

[reklein]

I forgot about the light 3/4 oz.glass fiber mesh one can get for R/C aircraft. That stuffs not too bad for this kind of work. Also while you in the R/C shop look for the light wood filler they use on model planes. I once tried using artists gesso as a filler. I found out later that the filler is marble dust which is of course rock hard. I couldn't even sand out the brush marks. . Also there are epoxy coatings which would make a nice sandable surface which would be very durable.  BILL

[puckotred]

Thanks all for the input. The cloth I am thinking of is 25 g/m². I believe that is pretty thin...

Piet, a most interesting build.

I'll try another couple of filler/sanding cycles before I venture into fiberglass and "Deluxe Materials Eze-Kote" that seems perfect for the job.

[JerryTodd]

You have to sand down all semblance of plank edges before any filler will do any good.  The danger is sanding through the plank.  You might consider actually plating her in metal.  A roll of aluminum duct tape, peel and stick aluminum sheet runs about $20 US and you get some like 20 yards of the stuff 4 inch wide.  Sand the hull, fill it and sand some more, seal it, prime it, and sheet it.  Nothing looks like metal quite like metal does.

Edited July 1, 2014 by JerryTodd

[AndrewNaylor]

Please for get FG the resins is very hard let alone the resin socked cloth. Car bondo is much easer to sand down and fair, do a test strip before you ruin all your hard work and send her for a "Valhalla"  funeral 

Andy

[puckotred]

(Sanding, filling, sealing and sanding on...)

[puckotred]

That sounds like a perfect solution Brian!!

 

I'll do that in about 10 days when I get my "Eze-Kote".

 

 

Thank you   

[NMBROOK]

I agree with both Piet and Brian.You can use epoxy finishing resin(I use a zap product as the 3hr drying time prevents thickening during application) or use the superfine woven cloth.The cloth does require experience and great care as unlike chopped strand mat,it takes a lot of work to conform to surfaces with compound curves.When using cloth,I always use a flexible credit card sized plastic scrapper to 'tool' the surface.This works out any trapped air and consolidates everything to give a minimum skin thickness.This also removes a great deal of resin in the process,it is surprising how little is actually needed.When this goes 'green' (set but still tacky) I apply one or two more coats of resin only,ensure no coat is fully dry between application,as epoxy does not stick to itself when cured without mechanical abrasion first.After leaving for at least two days(otherwise any abrasive will just clog up immediately) I sand by hand.Coarse wet and dry used wet with a little detergent added works best if you can get away with using it on your application.

 

Kind Regards

 

Nigel 

[puckotred]

Thanks for the feedback Nigel.

 

I'll have to go with the resin only as it would get complicated with the windows on top of the hull.

 

 

How is gluing stuff to resin? Or should I attach the wales and window decorations first? And will the resin hide the plank edges?

 

(or should I just paint the god damn thing and hope no-one sees the planks....?)

 

((I used some "sanding filler" I ordered from the U.K. that filled the pores of the wood nicely at least. The stuff is based on cellulose and I'm stoned just by opening the lid. I apply it to the hull outdoors and I see lots of lovely colours even though I'm colourblind!))

Edited July 13, 2014 by puckotred

[NMBROOK]

Hi Mr Pucko

Brian is correct,but he is obviously refering to polyurethane resin,epoxy hardly smells,whereas polyurethane resins are horrendous.Epoxies are a 50/50 mix,whereas polyurethanes you add a waterlike catalyst at a percentage of around 5%.If you detect any smell with Epoxy,it is a very mild 'fish' like smell.I haven't used polyurethanes on models for years as the 'open' work time is subject to far too many variables and can result in the setting process starting before completion of the work.Industrial quality polyurethanes are a little better,but still need fastidious attention to mixing for the correct ratio.

If the sealer you used is in a white tin with a blue label,I had problems with this crazing some months down the line due to natural timber movement.A superior product is called G4 and produced by the German firm Graupner.Unfortunately they recently went into administration,and whilst a new owner has been found,availability of their products is sketchy at the moment.

Looking at your build,I would apply epoxy(I recommend Zap finishing resin due to the 3hr cure time,the pot life is actually less than that).You are correct,the openings cause an issue with using woven mat,it can be done,but would be very hard to stop the resin running through the holes and making a mess inside.For mat application,cutting apertures after glassing is the preferred route,although I feel your windows came as part of a precut section.

If I were to do the job,I would apply several coats of epoxy finishing resin before adding any wales or details.With the zap product,you can apply coats at 90 minute intervals,this gives bonding between coats,but the next coat won't 'drag' on the previous coat.Several thin coats are prefered to a couple of thick ones,as this stuff goes on like paint and will run if applied too thickly.I would allow a full day for the job to be on the safe side and if working outside,avoid a warm sunny day.

It will take some work to sand smooth as you do end up with mild 'orange peeling' as the thickness builds up,but you can get a finish like glass that is durable.I wouldn't go further than 320 grit,this will allow you to affix the wales,preferably with normal epoxy glue and for small details like etchings,thick cyano will suffice.The final abrasive marks are better removed using aerosol car spray primer and flatting with wet and dry paper used wet.I prefer to use a 'plastic primer' designed for car bumpers first,this has adhesion promoters and ensures the paint won't lift at a later date.

I know this sounds long winded,but actually isn't as bad as it sounds,I just didn't wan't to miss anything out as it has taken me years of trial and error to develop a method that not only produces an exemplary finish,but will look just as good 30 years down the line,even if it is a working model and used in the water.

Kind regards

 

Nigel

[puckotred]

Thanks again for the feedback. The model will never see water, the procedure is solely for hiding any traces of planking.

 

I have ordered this stuff:

http://www.deluxematerials.com/boatezekote.html

 

They say it's easy to sand. (And I hope that's not a lie because I'm quite fed up sanding now... )

[NMBROOK]

No problem Mr Pucko,I can't advise as I have not used the product,however all experiences I have had with deluxe materials products has been good.I wish you the best of luck.

 

Kind Regards

 

Nigel