Glass Covering

[jonathan harper]

I am thinking of glass covering my next model (probably a Wot 4) - has anyone got any advice on how best to do this or does anyone know of any articles or web sites etc that give good instructions?

[Richard Wicker]

Hi Jonathon.

A lot of modellers have their own method of glass covering that they swear by, and it's one of those things that when you find a method that works well for you, stick to it!

The method I use if you want to give it a go is as follows.

I use SP113 resin, mixed as per the instructions. Give this a good stir to mix the resin & hardener, then add some surgical spirit, a drop at a time, and keep mixing until the mixture is only very slightly thicker than water.

I then use a 1" household paint brush to brush the liquid through the glass cloth which is laid over the area of the model to be covered, (A fuselage side for example) using just enough to dampen the wood under the cloth, but without dragging the cloth out of shape. Once this is done, leave for at least 12hrs at normal room temperature and you'll find that the cloth is stuck solid and the small amount overhanging the edges is stiff to the touch and can be trimmed off with a fine sanding block. At this stage you should still be able to feel the cloth weave if you run your finger tips over it.

Another coat of resin mixture, mixed as per the first coat, should just fill the weave, and this is enough!! When dry, the covering can now be sanded with Wet'n'Dry -used wet- starting with a medium grade, down to very fine, until a glass smooth semi gloss sheen is reached, and the job's done.

Some points to remember are:

This isn't a quick way to cover a model, so don't rush it.

Use any surplus mixture to "paint" the inside of the engine bay on ic models, it's a great fuel proofer.

NEVER try to fold the glass cloth around  tight edges, (wing l/e t/e, or the corners of a box fuz etc) it wont work and you'll have a hell of a job sanding it off!

Your brush can be washed out in cellulose thinners.

Once glassed and painted, you'll still need to fuel proof your model since the glass may be fuel proof but the paint isn't.

I hope this helps, it's the way that works for me. Please feel free to try it if you wish and good luck with your model.

Richard.

[jonathan harper]

Thanks for such a quick response.  A couple of points:  If you can't wrap the cloth round sharpe edges how do you deal with the joint between, for example, the fuselage bottom and side?  Are the 2 pieces just butted up against each other?  Secondly how do you deal with complex curves like wing tips?

[Richard Wicker]

Hi again.

Yes, if you cover the fuselage bottom first for example, trim this after the first coat, then do a side in the same way, then say the other side, then top, so you have the complete fuselage covered. Don't forget, the edges of the fuz are getting painted with glass twice in this process, (Where the bottom meets the side, side meets top etc). The whole fuselage is then given the second coat, (so the edges have had 3 in total). Once sanded, the edges will be just as smooth and strong as the rest.

Another point to remember is that glass resin has no shrinking property, so twisting out of shape isn't a problem.

Regarding your second point, curves, the glass cloth (I use light weight) will conform to small curves, however tighter ones should be covered in sections. At first you'll think it looks like a dog, but once the first coat has dried I bet you have to search for the joins,-& you know where they are!- After the second coat and the sanding, no joins will show.

Like anything else, practice first, and don't forget the weight. Try not to get runs in the resin, they take forever to sand off. If after the second coat, the weave is still there in places where you've been too sparing, another coat just to these areas is fine.

[jonathan harper]

Thanks again for your quick response.  I read somewhere that the weave could be filled with filler primer (from halfords) which would be easier to sand/finish.  Have you ever tried anything like that?

[Richard Wicker]

No, sorry, never tried that. To be honest, I hadn't heard of the idea before, but thinking about it now, I can't see a benefit to it beyond ease of sanding. Two coats of glass resin over light weight cloth will just fill the weave and sand to a superb finish, giving great strength and fuel proofing for acceptable weight gain.

Filler Primer would I believe, not be as strong, have doubtful fuel proofing properties, and I can't see it being any lighter. However, as i've said before, if it works for you, do it. Why not make up a couple of identical practice sections, then glass one and primer filler the other. Sand and finish them both, then subject them to tests for fuel proofing, wear and tear (Hanger rash), weight etc?

[Martin McIntosh]

Just thought that I would add a tip in a suitable place. When looking for something to sand a glass finish, I came across some 5mm thick wet or dry Oakey sanding pads in B&Q, available in 180 and 220 grit, used wet on the glassfibre. Thought that I would try them on bare balsa, used dry. Brilliant! They follow the contours exactly without any flats or dents and produce a silky smooth finish. Go get some! They are great prior to a film finish. MM.

[Richard Wicker]

Yes, they are good. Car Boot/ Market tool stalls also sell them in bundles of 3 or 4.

[jonathan harper]

I've now committed to a WOT 4.  The whole model is solid except for the wing tips which are made up of a framework.  How do I deal with this?  Is it possible to use the glass cloth like tissue or do I have to modify the tips to make them solid?

[Richard Wicker]

Sheet them with 1/16th balsa.