More compounding gelcoat novice questions

[tmjb]

I'm in the process of following Maine Sail's great advice re compounding and waxing my new-to-me '81 Hunter which has probably not been maintained in at least 20 years - may well be longer.

I wrote and got great advice a couple of weeks ago about wet sanding and buffing and have completed the wet sanding of one side. I have now started the buffing, about which I have the following questions:

My understanding is that you should expect to spend approximately 2 to 3 minutes per 2' x 2' area using the Presta Gelcoat Compound for a properly prepared surface. My question is how reflective should I expect the gelcoat to be after this step?

Also, I assume that in Maine Sail's procedure he classifies the Finesse It/Presta Ultra Cutting Creme as part of the compounding, although he calls for it to be buffed with the yellow wool polishing pad. Is this correct? Does it get applied in the same way, same 2 to 3 minutes per 2' x 2' area?

Any advice would be much appreciated.

 

[Brian S]

You should see some shine. Many people would probably think the shine after the compound is good enough. The Presta Cutting Creme is used with the yellow pad, and should lead to a surprising increase in shine. I find that the yellow pad generally scrubs off the Cutting Creme, so you'll know when it's done. You'll develop a feel for it.

To do the final step with the other product (I forget what it's called though I bought some this year) needs to be done with about 1500-1800rpm with a foam pad held flat. I used about 1500rpm given it says depending on hardness, and gelcoat is softer than paint. It's supposed to flash off, but I found it left residue that cleaned off with my Collinite paste wax.

 

[tmjb]

Many thanks for the input.

I forgot to add another question which is how much pressure should I apply to the pad when compounding?

 

[Gunni]

Use the Presta Ultra Cutting Creme and a BLACK wool medium cutting pad to remove the sanding scratches. The yellow pad has less cutting power and extends the job. Just press hard enough to keep the pad on the surface and working. Start slow, and increase buffer speed after you have applied the Cutting Creme.

 

[sesmith]

As Gunni mentioned above, Presta makes a black wool pad that is made to be used with the cutting creme. FWIW, when wet sanding, I don't stop at 1000. I go over it with 1200, then 1500. Then, I go directly to the Cutting Cream, and the buffing goes pretty quickly. Then finish with Ultra Chroma (and green pad).

 

[tmjb]

Thanks to you both. I much appreciate your invaluable insight and advice.

In using the Makita 9227C, in addition to finding it heavy to hold up on the surface of the topsides for a long time (so far its taken me about 3 ours for half of one side of my 36 foot sailboat) I also find that it tends to jump sometimes. I find that I keep having to spray mist both the pad and surface to keep it from drying out (it was sunny and windy so I'm sure that didn't help) and that that helps.

I am also not really clear how long to stay on a given speed. The dial is numbered with 1, 2 & 3 with 3, if I remember correctly, relating to about 2100 rpm, the top end of what Maine Sail recommends. He states that if you're spending more than 2 to 3 minutes on a 2' x2' area your using the wrong equipment, technique etc. So going slowly 600 to 1000 rpm, 30 - 45 seconds at 1000 (or does he mean in getting going from 600 to 1000?) and then up to 2000 rpm in 2 to 3 minutes doesn't seem to leave much time at any given speed(?).

 

[Gunni]

Until you get good at this you should stop and wipe the hull clean to inspect your progress. As your skill increases you will be able to work the compound off with the buffer. Change your hand holds up, even grabbing the body of the buffer with both hands (like a vase). Having a scaffold that can be adjusted up and down helps to get the buffer to below shoulder high -more comfortable

 

[Jumpstart]

Be very, very careful with that buffer. A close friend was compounding his hull with one a few years ago and caught a stray string hanging down from the deck. It wrapped around his finger and tore off his finger at the knuckle. Fortunately friends in yard heard him screaming and got him to the hospital ASAP as he was going into shock. They put his finger in ice but it was not savable. I now put the power cord over my shoulder so it doesn't catch on anything.

 

[tmjb]

Thanks again, both on technique and safety.

I do have a scaffold of sorts but it probably isn't tall enough for the top.

I almost had an accident with the power cord myself.

Re wiping the surface to inspect progress my question is what should I expect to see at the various stages.

Apologies for the novice questions.

 

[Gunni]

Re wiping the surface to inspect progress my question is what should I expect to see at the various stages.

The removal of sanding scratches (if you sanded) or swirls if you compounded. You are looking for shine. Keep that water spray bottle handy.

 

[tmjb]

Finally got to use the Cutting Creme - all my previous work had been wet sanding and compounding - and now I see a result much closer to what I was looking for.

My question about what I should expect to see was really after the compounding but given the result I am getting after the Creme it looks like what I had was good.

I do have a question re the spray bottle though: when compounding I was concerned about the compound drying during the process so was continually misting with the spray bottle. With the Creme the directions on the bottle said to apply to a dry surface and made no mention of spraying so, after trying without, I just misted very lightly to start and the result seemed good - with almost no splatter (there was plenty from the compound).

Also, following the directions to use about an inch of the Creme per 2'x2' area, I used much less of this than I did of the compound which I applied to the pad as Maine Sail indicates.

What do you think?

 

[Gunni]

Yes, the Ultra Cutting Creme is an amazing product. You don't use much and it is much easier to work than the compound because it doesn't gum up, dry and harden. You do want to keep your pad damp while you work each section. Rinse the pad when it starts throwing lot of dust.

 

[tmjb]

Thanks again.

Have you reconditioned well oxidized gelcoat with wet sanding and Ultra Cutting Creme, i.e. without the coarser compounding step and, if so, what grit did you go up to?

Thanks also re the diesel problem. No wax yet so that works fine.

 

[forbin]

I'll just throw in what I did this weekend just in case it helps...a slight variation of Maine Sail's recommendations.

I have a dark blue hull and it was fairly badly oxidized even after a year (I don't think it was done well and I certainly didn't do enough to maintain it.)

I found only one place locally that sells the Presta products and all they had in stock was the cutting creme. Being impatient, I decided to use the cutting cream with the compounding pad (3M #05711) as the compounding stage, which worked surprisingly well to bring back a nice shine. I had to go over a couple areas twice. Initially I had issues with the polisher jumping around but after about a third of the boat I had it under control, I think they key was controlling the pressure and keeping the pad clean. I didn't go over a specific area for a specific amount of time, I just watched for the creme to start to dry where I could see some shine coming through and then stopped. I waited around for the sun to be at the right angle and as I expected there were some very minor swirl marks, probably the result of the pad and this being my first time doing this.

The next day I went over it once with the cutting creme and the polishing pad (3M #05713) and the shine 'deepened' and there were no swirl marks at all, it looks amazing!

Finally, I hand applied two coats of Starbrite Marine Polish with PTEF. Starbrite recommends a second coat, the first to fill in the voids, and the second to provide a clean layer on top. This year, in an effort to prevent degradation I'm going to use a wash with polymers in it as well as applying another layer of polish every 1-2 months. I really want to be at the point next year that I can just hit it once with the cutting creme and the polishing pad and have it looking like new again. I probably spent 9-10 hours on the first side and with someone helping me about 4 hours on the second..phew.

Any suggestions on the best polymer polish (or other) for UV protection?

 

[tmjb]

Great input. Many thanks. Did you use any misting with water as part of what you did with the compounding and/or polishing pads?

What size and type of boat (power or sail) do you have?

Mine is a 35' sailboat and so far I think I've spent

 

[tmjb]

Obviously sent that prematurely:

... so far I think I've spent about 21 hours on it including the wet sanding phase and, assuming that each step including the polishing goes at about the same rate I estimate that I have about 27 more to go!

 

[sesmith]

A couple of things that work for me. On the cutting cream, you don't need much...no more than a silver dollar sized blob or so. Start slow to spread and increase speed up to around 3ish with the makita. I usually speed it up just a little over 3 to finish....very lightly and quick to finish. There will be very little to wipe off with a microfiber rag. Careful, though, too fast, or too much, and you burn the gelcoat. If the pad starts to gunk up and glaze, you're probably using too much. Anyhow, if it does this, or you find you're leaving too much behind on the boat, wash the pad in a bucket of water, and spin it dry (in the bucket). You'll find it works much better if kept clean. I rarely use a mister (only if it's hot and sunny)...key is small areas and not too much product.

One other thing I've noticed. After I start the buffing process with the cutting cream, I test a couple of areas after buffing by wiping with a damp rag. I don't know what it is with the cutting cream (presta does not add fillers) but if I see oxidation in the surface after it dries, I've gotta go back and redo things (usually by wet sanding more or going to a more aggressive buffing compound). It can look great until you wipe it off with water, and the oxidation shows up...don't know why, but if you don't do anything about it then, that oxidation will show up in the finished job within a couple of weeks.

I like to finish the job with ultra chroma. I usually speed up to about 2 1/2 - 2 3/4 on the buffer, and finish it at about 3. This goes pretty quickly. Keeping the pad clean for this step is pretty helpful to get good results. You should be able to fluff it back up with your fingers, between areas. If not, wash it.

I'm sure there are better, more correct ways to get the job done. I'm not a detailer, by any means, but this is what has worked for me.

 

[tmjb]

Many thanks. Great input.

 

[sesmith]

Any suggestions on the best polymer polish (or other) for UV protection?

I too wish I knew the answer to that one. I have used Rejex and didn't think it lasted as long as Colinite paste wax did (I put Rejex on the transom and Collinite on the rest of the boat that year). On the waxes, I also tried Presta's marine wax. This is nice stuff, but Collinite works better for me.

This year, I'm trying Starbrite marine polish with PTFE (2 coats) with a top coat of Collinite. I know that sounds excessive, but it's an experiment on uv protection. Previous owner of our boat used poliglow. I stripped it off. Since then, it's been a losing battle keeping the oxidation at bay. I can make that boat look brand new in the spring. The next season, I'm buffing it again. I would love to just have to hit it with a coat of wax and be done with it. I'm afraid that the sad truth is, once gelcoat gets oxidized (or poliglowed) it's never the same. I may end up going back to poliglow, if this years painful restoration process fails to last a while. Even if I can just get by with a quick buff and wax, I'll be happy. I was still stripping spots of poliglow off it this year (3 years later), so I don't love the stuff.

 

[Charles Erwin]

Collinite 885 - which is a hard paste wax with no cleaners and evidently no polymers in it - seems the best for this climate anyway. Collinite products can be gotten mail order (Amazon) but West Marine has this in several stores in the Pacific NW and Fisheries in Seattle has it. 885 is really best on a very clean freshly compounded surface. Lasts a good long time but probably not more than a year.

Collinite makes several other items that can be used alone or in combination and several contain synthetic polymers.

Check the Collinite website for their recommendations.

Charles