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Kevin Crisp
4-May-2010, 13:41
For those of you who have done this, could I get away with resin over plywood, with mat/tape in just the seams, or should I have Fiberglas mat over everything? Thanks.

bob carnie
4-May-2010, 13:46
Kevin

I use West Systems over plywood and have made many sinks that work well.
Very simple odourless and goes on like paint.


Bob

dsphotog
4-May-2010, 13:51
Yes, one of my sinks is 3/4" plywood coated with resin inside, (painted outside) only the seams are reinforced w/ fiberglas fabric.
I used brass screws & glued all the seams too. Very strong!
Oh, put in the drain before you apply the resin.

Richard Wasserman
4-May-2010, 14:08
Yes, one of my sinks is 3/4" plywood coated with resin inside, (painted outside) only the seams are reinforced w/ fiberglas fabric.
I used brass screws & glued all the seams too. Very strong!
Oh, put in the drain before you apply the resin.



That's how I did it. My current sink is over 20 years old and never a problem.

rdenney
4-May-2010, 14:20
I agree with Bob's recommendation to use the West System materials. Regular polyester resin used with home-laid fiberglass is not all that waterproof in the long run, but the epoxy resin used in the West System is. I would probably put a layer of fabric everywhere to prevent future cracks, but I think just doing the seams would probably be fine.

Rick "who prefers fabric to matting just for ease of application" Denney

Henry Ambrose
4-May-2010, 15:30
Yes, you can tape only the seams, but it is better to apply a layer of thin fiberglass cloth and two coats of resin over the plywood before you cut out your pieces. With your plywood laid flat you can get a nice surface build up. The resulting film thickness makes your sink really waterproof. The surface finish will be very smooth which is nice for clean up every time you use it.

I apply the resin with an adhesive roller then lay the cloth down on top. Let it cure and then the second coat goes on with a roller as well. When you assemble the parts, leave a small filet of resin in the corners and you're done - no tape needed. And yes, West System is great stuff. If you start in the morning and pay attention to the technique and timing you can finish the sink in one day.

On the other hand, lots of folks have built plywood sinks with yellow glue, slapped a couple of coats of paint on them and used them for years.

Henry Ambrose
4-May-2010, 15:36
To get the sink to drain well I put a little draft in the bottom at assembly. At each end I add a ledger of 1" material that the bottom panel sits on. I then apply resin and nail each end with my nail gun. Screws work fine if that's your preference. Then while standing in the sink at the middle, I shoot in the sides. The result (on an 8 foot sink) is a drop of 1/4 per foot to the central drain. I hope that explanation makes sense, if not, I'll draw to clarify on request.

Henry Ambrose
4-May-2010, 15:41
For the drain I use a hole saw to cut a hole that about the right size for the drain. If you don't have that big hole saw, use a jig saw to carefully cut a round hole. Dress up the hole with a rasp to make it nice. Then find the router bit that will give a profile that's close to that of the drain and make a cut that lets the drain recess into the bottom panel of the sink. Fit it all up and bed the drain with resin. Wax the drain so you can knock it out after bedding. Alternately, just glue it in with resin if you don't care about ever taking it out.

Ron McElroy
4-May-2010, 17:03
I used an expoxy paint on mine and they are still waterproof after18 years. The seams were lined with fiberglass tape before painting the sink. I finished the drains much like Henry.

Kevin Crisp
4-May-2010, 17:17
Thanks for all your helpful comments.

nolindan
4-May-2010, 18:34
use the West System materials.

The West system is designed for building boats. There is nothing better for putting over wood to make a waterproof system. I have seen some lovely wood boats that have been glassed: all the beauty of wood without the headaches and maintenance typical of a wooden boat.

Brian Ellis
4-May-2010, 18:35
Fiberglass is messy stuff, I wouldn't use it. I used a Benjamin Moore product called "Moorelastic," which was some sort of elastomeric paint. I'm sure other companies must make the same or similar product. Very easy to apply, didn't stain badly, and I never had a problem in six or seven yearrs. There have been a lot of posts here about building and waterproofing darkroom sinks, a search should turn up more information than you need.

Make sure your drain is in one corner of the sink, not in the center, and make the legs slightly longer on the opposite end so that the water will flow towards the drain.

dsphotog
4-May-2010, 20:06
Moorlastic sounds great!
My first sink was 3/4" plywood painted with boat hull enamel. Without any reinforcement.
I used it for 10 years until I outgrew it & installed a bigger one,
at that time I left it out on the side of the garage, it was watertight when I gave it away 5 years later!

Peter Langham
4-May-2010, 20:24
I have used epoxy resin followed by epoxy paint (probably overkill) on 2 sinks and never had a problem. Just caulked the seams, never used fiberglass fabric. I just found it easier not to use the fabric and I have never had a problem.

D. Bryant
5-May-2010, 06:34
For those of you who have done this, could I get away with resin over plywood, with mat/tape in just the seams, or should I have Fiberglas mat over everything? Thanks.

Whatever you do do not use fiberglass resin or elastomeric coating. The fiberglass resin is full VOCs (volitile organic compounds) and the elastomeric coating will eventually fail.

What you should do is use West Sytems Epoxy. I just rebuilt my sink and stapled 6 oz fiberglass cloth onto the bottom and sides and then coated with the West Systems Epoxy. I set my plastic drain first though. I routed a recess in the wood so the drain was flush.

There are some pictures here on the forum after my sink was finished. If you have any questions just send me a PM.

Don

CG
5-May-2010, 08:14
... do not use fiberglass resin ... I presume you mean polyester resin as opposed to epoxy resin. "Fiberglass resin" is something of a misnomer. Regardless, there may exist polyester resins without VOCs. See: www.admiraltymarinecoatings.com/fiberglass/partb/partb.html I have never used this product, but it might address that particular concern.

I am not a fan of polyester resin anyway. The last time I used polyester resin, the fumes were very nasty. Epoxy is much better in every way.

I wouldn't do a sink without fiberglass. Reinforced or not, the epoxy is expensive. Why not spend just a little more for a far tougher product?

Brian Ellis
5-May-2010, 09:58
Whatever you do do not use fiberglass resin or elastomeric coating. The fiberglass resin is full VOCs (volitile organic compounds) and the elastomeric coating will eventually fail.

What you should do is use West Sytems Epoxy. I just rebuilt my sink and stapled 6 oz fiberglass cloth onto the bottom and sides and then coated with the West Systems Epoxy. I set my plastic drain first though. I routed a recess in the wood so the drain was flush.

There are some pictures here on the forum after my sink was finished. If you have any questions just send me a PM.

Don

I guess it's hard to argue with "eventually" fail. We'll all eventually fail. But the elastomeric product I mentioned in my earlier post lasted for the 6 or 7 years I used it and gave no signs of failing. Plus it's so easy to apply that if you were really worried you could just reapply a coat every few years. It took me maybe 15 minutes maximum to paint it on the interior of my 3'x10' sink.

DaveAlbano
5-May-2010, 10:16
What about using a Rhino truck bed coating? DIY or pro application.

D. Bryant
5-May-2010, 11:16
I guess it's hard to argue with "eventually" fail. We'll all eventually fail. But the elastomeric product I mentioned in my earlier post lasted for the 6 or 7 years I used it and gave no signs of failing. Plus it's so easy to apply that if you were really worried you could just reapply a coat every few years. It took me maybe 15 minutes maximum to paint it on the interior of my 3'x10' sink.
Brian,

I know two people (one being myself) discovered that the elastomeric coating failed after 7 or 8 years.

West System Epoxy is superior in every way.

Don

D. Bryant
5-May-2010, 11:18
I presume you mean polyester resin as opposed to epoxy resin. "Fiberglass resin" is something of a misnomer. Regardless, there may exist polyester resins without VOCs. See: www.admiraltymarinecoatings.com/fiberglass/partb/partb.html I have never used this product, but it might address that particular concern.

I am not a fan of polyester resin anyway. The last time I used polyester resin, the fumes were very nasty. Epoxy is much better in every way.

I wouldn't do a sink without fiberglass. Reinforced or not, the epoxy is expensive. Why not spend just a little more for a far tougher product?

The epoxy is extremely tough. The fiberglass adds strutural integrity to the wood frame. There are plenty of people on this list that will vouch for West System Epoxy.

Don

John Dey
7-May-2010, 12:06
I second the vote for epoxy paint. Its much cheaper than fiberglass and the result is more attractive. I like to make my sinks with MDF. I carefully sand and fill the edges. I make very small Bondo fillets in the corners with a plastic putty knife. Then I finish with 3 coats of Expoxy paint. Don't think of it as sink so much as a counter top that's easy to clean when you spill stuff on it. And yes if you leave developer on it over night it will stain. But I can make a sink like this in 3 days for less than $60. (yes my darkroom walls are painted Mocha Brown. I live in Seattle -:http://farm5.static.flickr.com/4058/4587402698_a407cf45ec_b.jpg)

Rick Moore
7-May-2010, 14:38
The epoxy is extremely tough. The fiberglass adds strutural integrity to the wood frame. There are plenty of people on this list that will vouch for West System Epoxy.

Don

I can't speak for the West System in sinks, but I used to have a 25' Piver Mariner trimaran that was literally held together by the West System. Even after years in the sun on Lake Michigan, it held up well. Some of the beams in that hull will probably last forever, as they were coated with multiple coats of West System epoxy with the carbon fibres added for strength.


--
Rick

D. Bryant
7-May-2010, 15:22
I can't speak for the West System in sinks, but I used to have a 25' Piver Mariner trimaran that was literally held together by the West System. Even after years in the sun on Lake Michigan, it held up well. Some of the beams in that hull will probably last forever, as they were coated with multiple coats of West System epoxy with the carbon fibres added for strength.

I can believe it.

--
Rick