Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[john_k]

G'day all,
For some time I have been taking my first few stuttering steps into model sailboats. My first efforts at hull construction using balsa with epoxy resin glue went on the rocks when I discovered it is almost impossible to sand down prior to finishing as the epoxy seems to be almost indestructible. I am now trying another tack, using aliphatic resin glue with the balsa. Now my question is, if I am to give the inside of the hull a good coating of varnish I will have to varnish the inside of the deck before it is attached. Will the same adhesive still stick the varnish to the varnish, or does it only work with unfinished wood. Thanking you in advance for any assistance,
John Kearsley.

[Neil]

you would have to sand the varnish off the glued areas first.

[Seaspray]

Tricky rubbing down  the varnish as it would be in different thickness and you could penetrate into the balsa. Balsa is classed as a hard wood but is soft as putty I personally hate balsa prefer ply. I've used Aliphatic glue to do the planking on the Meteor (soon to be relisted) and it did a treat wood to wood. Yep epoxy is bullet proof and the 5 min cure one . I don't think it lasts the ages of time like the slow cure. There is balsa glue which I thought was a laugh when I was young lad and still to this day. There is a product called Sanding Sealer  which I  have used on balsa but it take a good few coats to work but this is not a glue it a sealer as it name implies. I might consider putting that on the inside of the deck. See what the other mems say. A pic of the build would be nice

[Circlip]

Balsa is classed as a hard wood but is soft as putty

  Obviously never come across hard Balsa then. It depends what cut the wood is from, looking at the surface will tell and also the colour.
 
  Glue, Aliphatic resin. Sanding sealer is for grain filling. If you build the basic structure using Aliphatic resin, any panels you want to waterproof on the inside, such as the deck, can be "Painted" with a few coats of clear dope, this is sanding sealer without talc filler. When the panel is dry you should glue it to the frame with Balsa Cement which will fuse to the doped surface. The model can also be covered using dope and tissue which leaves a smooth surface for painting with an enamel type paint.
 
  Sadly, many of the older construction methods and materials are being lost thanks to the brigade of instant gratification.
 
 
  Regards   Ian

[Seaspray]

Yes agree about old school methods and the smell of those chunks of glue melting in the pots off yesteryear. and Cascamite glue. Another glue I really like is R/C Modellers glue from Deluxe  Material. It stuck clear plasticard to my ply cabin to give nice clear windows Just letting  John_K know he has a job on his hands I try and stay away from the dopes but have in the past used resin on the inside of planked hulls to seal em.

[Circlip]

Definitely not advocating the use of animal or "Hide" glues, but there was life before epoxy and the "cyano with everything" group seem to forget that cyano is actually water soluble. X-boxes and Nintendo have a lot to answer for.
 
  Regards   Ian.

[derekwarner]

As Circlip notes .."but there was life before epoxy and the "cyano with everything"    ...that animal glue [3/16"light brown spheres] was sealed in tin cans prior to tipping in the water heated glue pot
When we constructed practice joints in Woodwork......that glue was indestructible.....  ...Derek

[Seaspray]

Heated glue was the strongest I've known bit of a smell to it as well.
 Now how is John_K problem with his hull. Any nearer being solved ?

[grendel]

you used to be able to get a waterproof version of cascamite that was very good, when I was being taught woodwork, everything was cascamite or the very smelly hot animal glue.
Grendel
ps - could you not mask the areas for gluing with masking tape before varnishing?

[Colin Bishop]

You can still buy Cascamite under different names:
http://www.amazon.co.uk/Cascamite-500g-Tub-Extramite-Adhesive/dp/B0001OZIA2
Colin

[Circlip]

Cascamite always was/is waterproof? 
 
  For anyone using or wanting to  use it, when mixing, add a couple of drops of Methylated Spirits to the mix, it disperses the bubbles.
 
  Probably too slow setting for todays high speed life. Gave you time to shuffle the bits to align them properly. Also allowed you to wash the excess of yer fingies.
 
   Regards  Ian.

[grendel]

Cascamite (I was told/remember from 30 years back) was water resistant in the original form (softens with continual immersion), but I thought there was a waterproof version they brought out. I have seen furniture made with cascamite that when parts broke off it left wood attached to the glue joint - so the bond was stronger than the wood. I did make some outside furniture using it and had the glue bond soften after a year or two (it was a very waterlogged wood though (greenheart))
Grendel

[dreadnought72]

ps - could you not mask the areas for gluing with masking tape before varnishing?

^ Do this. Since you know where the supports are going to be, you can mask off the underside and varnish.

Andy

[John W E]

Hi there John
First of all, before we get too sidetracked about gluing and varnishing - could you give an indication of what model saleboat you are making because you may be giving yourself more problems and looking for more work than is actually required.   If you are building a standard yacht - what I have known some of the lads at our club do - is to glue the deck directly onto the hull, sealing it well around the edges and having no opening in the deck at all at this present time.   When the deck is firmly glued in place & has been left to harden off, what they will do is drill a small hole where the mast is to be placed through the deck and pour either varnish or fibreglass pure resin with hardener mixed, through the hole and then seal the hole up with a bit of tape agitate the hull upside down for a good 10 to 15 mins so the resin/varnish is spread around evenly all around the inside of the hull.  Obiously you will have to do this about 2-3 times so it covers/coats the internals of the hull.    This is then allowed to dry and you know you have sealed the underneath of the deck/internals of the hull/also you have created an extra bond around the deck and hull.
Hope this is of some help.
aye
john e

[john_k]

Gentlemen,
First of all, thanks for your interest, I was resigned to further "(e)poxy" experiences. I have just received plan MM2070 "Jenny" from My Hobby Store. She is a 25" gaff? rigged pond yacht. I have re-scaled the plans to give me a boat of (almost) 36". I am presently getting materials together, so pictures will only come a little later. Circlip, dope with balsa cement, I could go for that (also dabble in vintage model aircraft). Definitely "superglue" is out. When I was an appy (circa nineteen sixty something) we had yellow Loctite (even then) but you had to have a firearms license (or the Foreman's permission) to use it. Looking forward to any further enlightenment,
all the best John K.
P.S. I used to sail "Fiona", a 24" bermuda rigged pine block with a 1/8" thick steel keel at Hove lagoon around 1960 (but not when the vane "A"s were busy at the weekend).

[john_k]

Hello again,
Further to all the above I have just concluded a very simple experiment using two pieces of scrap 3mm. balsa. These were both given three coats of varnish, including the edge to be joined. Parts were left for 24 hours between coats. A bead of aliphatic resin glue was then run along the edge of the one piece and the parts set at 90 degrees to form an inverted "T". An attempt to dismantle the assembly resulted in breakage of the vertical piece above the small fillet of glue which had oozed out when the joint was assembled. I am presently busy with a "quick and dirty" build to enable me to test the servo module which I assembled with the idea of using it in several different boats. I will glue varnish to varnish and see what happens.
Tks John K