Gummy Epoxy Finish

[Steve H Graham]

Still trying to develop the skill to fill the pores on my walnut guitar and apply a clear finish.

I put two coats of epoxy (West) on it, allowing a day in between coats for curing. Tonight I went over it with a scraper and sandpaper. I had problems.

There seemed to be gummy places in the epoxy. There were places where I could not get a shiny finish, and I could scratch the epoxy with a fingernail. The epoxy stuck to the scraper in places, and the globs on the scraper caused scratches to appear when I scraped.

I know I mixed this stuff correctly. I used the West dispensing system. I know I mixed it well. I really hammered it for over a minute. I know the temperature was over 70 degrees, so it had time to cure.

Any ideas?

I bought a can of Behler neutral pore filler. I'm going to see if it's any better.

[Howard Acheson]

>>>> There seemed to be gummy places in the epoxy

That is a symptom of either not using the correct proportions or, more likely, not mixing the two components completely. Mixing must be done carefully and completely.

[Mike Hollingsworth]

I gave up on that stuff.

[Henry Ambrose]

A mixing problem, I think.

[Steve H Graham]

I mixed the daylights out of it. Maybe I should have gone another minute.

[Scott Holmes]

Any chance the epoxy components were old or contaminaed in the pump tube from setting a long time without use?

[John Coloccia]

George Wilson uses this technique. He recommends removing the excess epoxy from the surface early when it is still gummy so that you don't have to scrape and sand HARD epoxy. Anyhow, it was almost certainly not mixed correctly. As far as I know, West does not expire. I've used cans that are a decade old with perfect results. The hardener will darken a bit but everything will still work with no degredation in performance other than it will be a little darker.

Most people mix by stirring. That works but it helps to go in figure 8's occasionally too. Also, you must scrape the sides and bottom. Enormous amounts of material can stick to the sides and bottom without ever getting mixed in. This is probably the main source of most people's problems. Then you'll end up with exactly what you're seeing....most of it is fine, and some of it just never really finishes curing.

Do you have someplace particularly warm in your house, like next to a fireplace or something like that? Try getting it warm (not HOT...just warm ). That will speed up any slow curing that's still going on.

[Henry Ambrose]

+1

What John wrote mirrors my direct experience.

[Steve H Graham]

I guess it had to be a mixing error. I don't know what else could explain it. I thought going way over the recommended time would get the job done, but I must have done something wrong.

[Henry Ambrose]

Warming your resin and hardner a bit before dispensing will help a lot to get good mixing. Warm means maybe 75 or 80 degrees where the materials flow freely. If you keep your epoxy in a cold garage its not gonna mix well while thick as honey. After its mixed, set the cup in some ice water to slow the reaction. This will give you more open time to glue up.