fiberglassing over MDO

Is there any reason why one could not glass over MDO plywood?

As I understand it, the MDO surface is compressed wood fiber, so I can't see that there would be any issues using proper prep methods, but would like other opinions.

 

What are you going to do with it, or what are you trying to achive??

 

There is definitely NO reason why one should, or could not cover a MDO with a glass/resin compound!!!!!!

The question is : what is the goal? does it make any sense? Do you have to much money?

At least one of the questions above should be answered to get a better response on your query.

Regards
Richard

 

MDO has resin soaked paper face(s) on one or both side over a WBP adhesive, minimum ply count sheet. It's questionable if you'd want to bond to this paper, though my tests have shown it's very well stuck.

For best results, you should abate the paper off, down to the surface veneer, then bond to this.

 

I've found mdo plywood to be one the secret good deals around here in Puget Sound country. Pretty decent quality, holds up to the weather nicely, reasonably priced. The paper is almost impervious to ill treatment. It's a delight to work with. I'd risk fiberglass on something small and see what happened.

 

I"m restoring a 34 year old dory style powerboat (23') whose hull was originally sheathed with two layers of 5/8" MDO plywood. I want to epoxy and glass the hull up to the waterline for abrasion resistance and some stiffening.

I will not be glassing the interior.

 

I am shure we have to make clear what YOU understand to be MDO
???????

 

A lot of manufactures used MDO back then. It use to be pretty good stuff, but quality has declined dramatically in the last 15 years.

You will gain no additional strength from a light weight sheathing, but will increase abrasion resistance substantially. Go for it.

 

I understand MDO to be exactly what the American Plywood Association describes it to be.

 

Sorry, my mistake, I was mixing MDF and MDO in my old brain.

 

The APA's rating system is voluntary in the USA and by no means any guide, as manufactures pretty much do what they want. The only things that seem to actually follow the APA recommendations are WPB adhesives and species selection. Defects permitted, repairs, voids, general construction, etc. all seem subject to whim by all but a few mills.

Your approach seems fine Film842, though I would recommend coating the bilge areas as well, to protect against sweet water pooling there and causing trouble. Better yet would be sheathing the bilge areas lightly for abrasion reasons only. Don't try to wrap over or around stuff, just flat places where a tool or bit of gear can roll around or bang into something and dig up some wood.