Teardrops n Tiny Travel Trailers

since this has been asked and reasked over the last year and a half, i am going to make this a sticky. it will help save gpw's sanity.

75% Mineral Spirits - 25% Cheap Polyurethane varnish... Well proven , Thrifty Waterproofing mixture... Get the common “Paint thinnerâ€

Well, looks like we have no arguments anyway ... ...

“Paint thinner†... what’s that ?

So, what's the shelf life of the mix and what can i store it in?

Shelf life ??? Who knows , I just store it in the vessel it came in ... I just mix a gallon of “Paint thinner†with a quart of poly (put a quart of the “Paint thinner†on the side to clean up with) ... ... use what you can (more coats the better) , put the rest back in the jug/can... use that later ...
I always find something else to waterproof around the house /studio/shed. so usually end up waterproofing something else , while I have it out and the brush is still wet ...nothing goes to waste ...

ok, so is that the oil based poly or the water based poly? (oil based is cheaper, don't do it without proper ventilation(!!!) and takes longer to dry.
paint thinner or mineral spirits? which?

You can't mix an oil base thinner with a water based poly. Since you are adding something that has a much higher flash rate than the poly it actually dries much faster than straight poly would dry.

Steve’s right !!! Can’t (shouldn’t) mix oil and water based products together ...
If you look on a jug of $3/gal paint thinner , the contents read... Mineral spirits ... the jug of "mineral spirits" is $9/gal ... why use the expensive stuff? It’s only going to evaporate anyway ... just a “carrier” for the poly ...

I was reading on the Net and came across GPW's special sauce being used to --- wait for it --- waterproof wood.

They used a 50/50 mix. Looked really good after.

Bonnie

OK, so that's for plywood, what about the rough particle board. Wood chips and such compressed into a board with some glue. (you'd have to look at one of my links to the raw surface...

PC , it works even Better on particle board , OSB , MDF, etc... I used it on my Jayco floor repair , which soaked it up like a sponge ... Too bad they didn’t do that at the factory or the “mush” never would have happened ...

i was reading a post the other day. on his build he just covered with diluted t2 for waterproffing on his wood. i was actaully just thinking of doing the same thing.

I'm definitely going to use GPW's recommended poly/mineral spirits mix to waterproof the exterior...and the galley surfaces that could be exposed to a suudden shower if the hatch is left open. But, I am unclear about whether or not the other side of the plywood should be completely sealed or not. I was told by a painter that the wood had to breathe. But I've painted some 4"x4" posts (w/ Krylon red rattle can enamel) that I used for wheel stops on my dragcar hauler, and it has been totally exposed to all weather for 6 years with no sign of deterioration. So what do you guys recommend...seal both sides completely, seal one side only, or leave a small patch on one side unsealedso the "skin" can breathe ( remember Goldfinger )?

Toughie, cuz I usually prefer the water based for soap and water cleanup, fast dry time and no fumes. Such is life, at least the oil based is almost half the price of water based.

Be advised, from what I understand, standard poly is meant for indoor use and does not resist against deterioration due to ultraviolet rays. From what I understand you'd want a "spar" poly for exteriors. If temperatures crackle the finish you might be back where you started from, unless you coated annually (or regularly).
http://www.minwax.com/wood-products/exterior-clear-protective-finishes/minwax-helmsman-spar-urethane
http://www.google.com/products/catalog?hl=en&q=spar+urethane&gs_sm=1&gs_upl=1759l3077l0l7138l5l5l0l0l0l0l245l679l0.4.1l5l0&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&biw=1006&bih=691&um=1&ie=UTF-8&tbm=shop&cid=16111896457739733780&sa=X&ei=GWVKT8y6NNPogAeakr3WBA&ved=0CFEQ8wIwAg
http://www.google.com/products/catalog?hl=en&q=spar+urethane&gs_sm=1&gs_upl=1759l3077l0l7138l5l5l0l0l0l0l245l679l0.4.1l5l0&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&biw=1006&bih=691&um=1&ie=UTF-8&tbm=shop&cid=18422028517744283143&sa=X&ei=GWVKT8y6NNPogAeakr3WBA&ved=0CFcQ8wIwAw

ok, next challenge, I have fiber board (looks like paneling, but is made up of more like pressurized cardboard, 3/16ths thick, with a lamination on the one side. I tried to protect the lamination, but I can't get oil or water based poly to stick. Is there a completely optically clear primer? (I'm worried what the thinner would do to the lamination. Ah, for the good ole days when paneling was at least real wood!) Should I be using this water proofing formula on the back(s)?

I used mine inside , outside , everywhere... No problem with UV , You Paint over it ... Just a waterproofer, not a final finish ...
Ps, I’ve been a painter for most of my 63 years ... wood that breathes soaks up water ...