I recently asked about the best varnish to use on a cabinet for a boat cabin and got some very good advice. The client has given me the varnish he uses and I have a couple of questions about applying it, since I’ve never done this type of project before.
The product is Goldspar Polyurethane varnish, made by Interlux for use on boats. The instructions say to thin if necessary (up to 10%) with their thinner, which is Brushing Liquid 333. It really necessary to use their proprietary product or can I use regular mineral spirits like I would with ordinary poly? Can I thin more than 10% and do I really need to apply a sealer coat, again using their sealer? The cabinet is made of cherry plywood with solid cherry edges, trim, etc.
One last thing. I have a Turbanaire HVLP sprayer. Can I spray this varnish or should I just brush it on? I can take the necessary precautions when spraying, (exhaust fan, resprator mask, etc.) so fumes shouldn’t be a major problem.
Thanks in advance for any advice you can give.
Replies
wooddood, any thinner will work and the 10% is a place to start,yes you can always thin a bit more then the recommended amount.No you do not need to use there sealer,sealing with the product it self that has been thinned will be fine. and you could spray or brush its personal choice really,the fumes from this product is not a huge issue ,a fan to keep over-spray from landing on you piece and Bobs you uncle.
Dan
Be carefull by mixing thinners with modern pu paint. Here is a link to a boatbuildersforum specially about paint etc. If there is not sufficient info. you can post a question there. Very nice people there (like here!!). I am building a boat designed by Mertens from http://www.bateau.com.
Here is the link http://forums.bateau2.com/viewforum.php?f=4&sid=8684b7ca26061419b736e2bafdd2eeeejaapEdited 7/19/2009 5:16 pm ET by jaap
Edited 7/19/2009 5:39 pm ET by jaap
Thanks for the links. I couldn't find the exact thread on the page. Could you point to which one?Which model of those boats are you building?
Thanks
The Brushing Liquid 333 will retain the relatively long working time for the Interlux varnish since it contains a mix of both fast drying solvents (Naphtha) and very slow drying (one that is virtually kerosene). The fast drying part flashes off quickly to avoid sags and the slow drying part allows brush strokes to still flow out after tipping off. Is it necessary, no, but I have paid for it on occasion. The problem is it is a bit hard to know about quality of other thinners. For example, I wouldn't use low odor thinner due to less solvent power, and I certainly wouldn't use things labeled as being green or the like. I might consider VM&P Naptha of a good brand if I could tolerate the somewhat faster flash off.
If you are spraying component parts in a real booth that can evacuate overspray quickly and safely, you can spray it, but no way you should spray within a boat interior. You would have to seal and mask EVERYTHING both inside and in the exhaust path. You'll have the first coat done, the brushes cleaned and be half way through your after hours beer before you could get the masking done.
You will definately need to thin the varnish even for brushing. As with all oil-based varnishes there really isn't a limit on the amount of thinning, though if you thin a lot you might need and extra coat. I am not really convinced that heavy thinning of the first coat is really needed, either. It does dry quicker because of being thinner, but these varnishes remain fluid long enough that any difference in "penetration" with the thinner varnish would be insignificant.
> mix of both fast drying solvents (Naphtha) and very slow drying (one that is virtually kerosene). The fast drying part flashes off quickly to avoid sags and the slow drying part allows brush strokes to still flow out after tipping off.Steve,Well said !rocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
Edited 7/19/2009 7:12 pm by roc
I've used a variety of Interlux products and I've gotten good results following their instructions and using their proprietary products. Call me a chicken, but it seems like cheap insurance on a project like a boat.
Like Steve, I have done a lot of marine finishing. In fact, I learned my finish initially as a painter in a boat yard. Interlux makes some good products and the Goldspar is an excellent product. I am a firm believer in using the product as directed by the manufacturer. Their thinner, as Steve notes, is more than a mineral spirits. If you use their products and follow their instructions you will have the best chance of satisfactory results. It's not worth taking a chance.
Thinning will probably by required to get good flow out. But their is a small margin of error getting to the point where the finish will drip and sag. Good brushes and brushing technique is very important and I suggest you practice on some scrap before committing to the actual job.
Finally, you don't want to spray inside the cabin of a boat. The overspray from oil based finishes are liquid droplets and will get all over everything leaving a crust when it drys.
It really necessary to use their proprietary product or can I use regular mineral spirits
It's a boat! You must use whatever costs the most. Don't forget the titanium screwdriver to pry open the can with.
Don't forget an expensive brush too. I have a couple of "ovals" and they're all I use with varnish. Here's a link.
http://www.woodenboatstore.com/Brushes/products/114/
Edited 7/20/2009 8:51 pm ET by Quickstep
Is it essential to a good varnish job to have a really good brush, no but a better than minimum brush will make the job easier and feel better. For example, Purdy ox hair or Corona ox hair mixed with China bristles work fine and should be in the teens for a 2" size, which is the most I would even think about for most varnish work other than hugh panels. You can pay $50 or $75 but it's not necessary. Cheap $6 brushes shed bristles beyond the first few minutes when all brushes do. They release varnish less evenly, making it harder to get rid of brush strokes and easier for sags or runs to develop. Even they can be made to work. Shoot a pro finisher I know even likes foam brushes, which would be my absolute last choice.
More important than good brushes is good lighting, both bright enough over all, and with enough at a low angle to reveal defects and misses immediately, not an hour after you have finished with the coat and can't do a thing about it.
And, even more important than either is patience. Trying to hurry gives rise to defects that ultimately take longer to fix. Now there are some who profess to making every brush stroke at glacial pace. I can't go that way, but occasionally repeating a mantra helps.
Thanks for all the advice. I started today with a Purdy brush from HD- around $12.00. Jeez, this stuff is like painting with molasses cut with honey. Very thick and viscous. Or viscious, I don't know which! I'm assuming that subsequent coats will go on easlier. I decided not to spray because of the viscosity and my overall lack of experience with anything other than lacquer.
I'm pre-finishing (is that a real term?) before I do any assembly so consequently all the panels are flat and fairly easy to apply the finish, but again I'm not used to brushing on syrup. I'm sure it'll end up just fine once I sand and recoat- and recoat- and recoat. Apparently with boat furniture you need to give it a lot more coats than you do indoor furniture.
I'll post photos when it's done. Assuming I can get it unstuck from the shop floor.
Just grousing beacause it's been a reeeealy long day. I'm confident I'll be able to handle the challenge of using a new type of finish. Woodworking should always punch our buttons; how else will we learn and grow/
alancarterstudio.com
It need not be syrup. That's what the thinner is for. Adding 10% (or a bit more if needed) will let it flow out much more easily. This is the one place on the manfacturer's instructions to ignore. They say do not thin for regulatory reasons not because they mean it.
The bristles on my Ovals are a bit stiffer than on "regular" brushes and make it a little easier to move syrupy stuff around. I've read articles in Wooden Boat magazine in which they immerse (not submerge) the can of varnish in hot water to lower the viscosity. I've never tried this, but it sounds plausible.
Interestingly enough, Epifanes addresses this issue on their web pages. They report that about equal numbers of customers around the world have told them they prefer to chill the finish before application as have told them that they like to heat it. They express no preference. Personally, I don'e see a reason not to to get the viscosity you want with thinner. The thinner doesn't participate in the final finish.
My shop teacher in 1975 would always put his varnish in a hot pot of water. Said it got rid of bubbles.
Yup, probably would. Thinner would too. Both are right--it's a matter of taste and how you learned. I suspect that the heat would last less long when actually applied to the surface that would the thinner. That could be good or bad depending on how you worked, and the risk of runs or sags.
Steve. always appreciate your input. Up here in the winter humidity is a concept. You have to account for - humidity. I still do plaster work for an orthopedic shop. In the summer takes 1+5 weeks for a cast to dry in January they dry 3 - 4 days
Shellac is a go to item. Radiant heat floor also adds to dryness. don't put a can of open paint on the floor. Wipe on varnish is the choice up here can do many coats a day. If it is thinned the humidity doesn't seem to bother wet or dry. Shellac will dry before your eyes when it is -40c out side.
The season may dictate the finish routine.
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