A MUST SEE- radical way on plywood epoxy finish job

[adam_designer]

Hi people,

I was opening some thread about epoxy glass on plywood in this link
http://www.boatdesign.net/forums/wooden-boat-building-restoration/peel-ply-plywood-epoxy-18832.html

Then Pericles, directed to a link from duckworksmags which is
http://duckworksmagazine.com/03/r/articles/glass/bottom.htm

which is - for me- is very radical way on finising job. okay here it is

normally you'll get this when you laminate woven roving over plywood

but if you use some step by covering it with plastic and rubbing the surface to pushout bubles

you will get this:

one word. AMAZING. the site stated

"I suspect that if more people saw this film procedure, it would become standard practice"

I cant more than agree with him. Then I have several question.

1. what kind of plastic it is? What it usually used to?

2. is the plywood need to be coated first with epoxy or just in one way?

2. I have some idea on wood deck finishing, will this work?
I will make some trench using rooter on plywood, but the "trench" or perforate lining is not totally cut the plywood. and then filling the trench with some rubber paste or black coloured resin. Then I will apply woven roving and epoxy on ot used the same technique ( I will not use non woven fabric, because it has some thread/ weaving thread that wont dissolve with resin, so it will have white yarn that not transparent) will this technique would be like this?? (but surely it would be glossy)

after that i will spray several PU coat for UV resistance.

Any comment and advise will be appreciated. Thank you

Adam

 

[rwatson]

Yes, its an old trick -


1. what kind of plastic it is? What it usually used to?

its Mylar. You can buy it from most 'glass shops., The downside is that the surface must be totally developable, or you get ripples in the surface.

2. is the plywood need to be coated first with epoxy or just in one way?

Generally, its easier to do a 'dry' wetout, with the cloth being saturated in stages. This solves the potential problem of the epoxy going off before you finish the whole area. You will need to apply the Mylar before the epoxy gets to solid. A warm air blower will help ensure a good wetout.


PS 2. I have some idea on wood deck finishing, will this work?
I will make some trench using rooter on plywood, but the "trench" or perforate lining is not totally cut the plywood. and then filling the trench with some rubber paste or black coloured resin. Then I will apply woven roving and epoxy on ot used the same technique ( I will not use non woven fabric, because it has some thread/ weaving thread that wont dissolve with resin, so it will have white yarn that not transparent) will this technique would be like this?? (but surely it would be glossy)

This may need to be done in a bit different order. If you try to epoxy the deck after routing, the fibreglass wont sit in the grooves. Consider applying the epoxy before routing ( with glass if needed ), then after routing, apply plain epoxy in the grooves for waterproofing. The 'filler' you need in the 'joins' should be Sikaflex. Apply it with masking tape on either side of the 'groove', and when the Sikaflex is getting firm, pull the masking tape up to leave a clean line.

 

[adam_designer]

Rwatson,
Thanks for your reply. Yes, some people knew this, but Hardly I cant find other sites or youtube's covering this trick.

Accidentally, I have some experience typical with this trick when i was infusing perforated core without mesh and peel ply, but i didnt think it would practicable

Yes, its right, if the plastic folded or not perfrcly fit, it will leave some spike/ linings just like when we infuse perforated core without peelply and mesh.

 

[adam_designer]

This may need to be done in a bit different order. If you try to epoxy the deck after routing, the fibreglass wont sit in the grooves. Consider applying the epoxy before routing ( with glass if needed ), then after routing, apply plain epoxy in the grooves for waterproofing. The 'filler' you need in the 'joins' should be Sikaflex. Apply it with masking tape on either side of the 'groove', and when the Sikaflex is getting firm, pull the masking tape up to leave a clean line.

I will fill the grooves with sika or other stuff before fiberglassing with epoxy, Thus the laminate will sit on the filled groove. I just worried if the routing process is after the fiberglassing, the edge of grooves will not be perfect, small crack of fiber-epoxy along the grooves.

 

[rwatson]

I will fill the grooves with sika or other stuff before fiberglassing with epoxy, Thus the laminate will sit on the filled groove. I just worried if the routing process is after the fiberglassing, the edge of grooves will not be perfect, small crack of fiber-epoxy along the grooves.

Not such a good idea. The edges of the epoxy will flex over the top of the Sitka, and let water in to run under.

Yu need to get the epoxy to completely waterproof the hull, as you cant rely on a join between the epoxy and the Sikiflex

By the way, the Sikaflex should be sanded about 1/8" above the epoxied deck for foot hold and deck protection. This can be down with abrasive wheel. I have seen it used very effectively on much larger boats as well.

 

[adam_designer]

Not such a good idea. The edges of the epoxy will flex over the top of the Sitka, and let water in to run under.

Yu need to get the epoxy to completely waterproof the hull, as you cant rely on a join between the epoxy and the Sikiflex

By the way, the Sikaflex should be sanded about 1/8" above the epoxied deck for foot hold and deck protection. This can be down with abrasive wheel. I have seen it used very effectively on much larger boats as well.

Oh yes thats right, well I see the point.

 

[lewisboats]

It is .030 Polyester (which is a bit hard to come across). I usually use the thickest Vinyl sheet that you can get which does the same thing. It is also more readily available where I live. Most any kind of plastic sheet which epoxy doesn't stick to and that you can get in thick enough and large enough sizes will do. Vacuum bagging in addition will maintain the compression on the cloth even more for a thinner but denser layer of cloth and resin, with a higher cloth to resin ratio.

 

[Yellowjacket]

This technique has been around a while and has been discussed at some length in other threads. Do a search on Mylar and it will likely come up. I've used it and it does work, but it's not the be all and end all, there are downsides to it.

The biggest downside is that it can be very difficult to get every last small bubble out, and EVERY bubble is a mess that you have to deal with later. For that reason I've had better luck with more flexible materials like vinyl than the Mylar. The vinyl doesn't produce as flat a surface, it has more gentle waves in it, but it is far easier to get all the bubbles out of the vinyl.

While the advocates of the process say that the layup is thinner, and it might be, it doesn't seem that a lot of goo gets squeezed out of the layup, and you can get a starved layup of you roll it too aggressively. For those reasons I've used it lately as a finishing technique. First I do the layup, and do a conventional squeegee of the cloth, and then, as that gets set up, come back and use the Mylar trick for filling the weave. If you just use the Mylar over the wet cloth, you can float the cloth and end up using a lot of resin. There is no question that it works and can save you a lot of work, but it isn't as perfect or as easy to use as that article makes it seem.

Just my experience with it...

 

[upchurchmr]

Adam,

Write the Duckworks site owner.
His comment to me was that it only worked for stitch and glue (developable) surfaces as was said above.

As I remember, it was tried once and had too many problems to continue with. This was the comment 2nd hand from the writer of the article.

 

[rwatson]

...... First I do the layup, and do a conventional squeegee of the cloth, and then, as that gets set up, come back and use the Mylar trick for filling the weave. If you just use the Mylar over the wet cloth, you can float the cloth and end up using a lot of resin. .....
Just my experience with it...

Spot on - that's the best way to do it for sure.

 

[Tungsten]

Yellow jacket has it right,heres a pic of 6oz on meranti all wet on wet.I should have did the mylar as a fill coat after the first coat went green.

This was with .020 mylar.Petg I think its called.

 

[adam_designer]

guys, Thanks for advice and share

Well, I do believe it wouldnt as simple as thepictures. But could be some consideration for me and others as well.

I think it would be practicable and "safer" to work in deck or other flat surface for small boats. I do have plan for it might be on next week and I'll show you mine. Thank you.

Will be appreciate other's experience on this technique.

 

[Herman]

Also make sure you test the mylar beforehand. Some surface treatments make it stick, and also older mylar that used to work, suddenly adheres to the epoxy.

And after all that work, you will still need to apply some kind of paint...

 

[Tungsten]

One thing it does do is leave you with a flat wrinkle/bubble free surface when applied over your wet glass.If left to cure fully before its removed it can be re used.Plus you have the other side to use.The blue is just the protective film that comes on both sides.i left it on the top side as its easier to see the bubbles through the blue.

 

[aaronhl]

I like this!!!

Can I buy blue Mylar at Home Depot or Lowes?

Do I have to use fiberglass or can I just roll mylar over expoxy resin?