This is my fifth build and the fifth time using tru oil. This problem has occurred before but not this bad. I’m sure someone knows what’s causing this streaking and how to fix it. I’d be very grateful for your help.
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This is my fifth build and the fifth time using tru oil. This problem has occurred before but not this bad. I’m sure someone knows what’s causing this streaking and how to fix it. I’d be very grateful for your help.
My understanding is that maple is very prone to blotching and streaking in finishes, especially ones that are absorbed such as oils. It is caused by uneven absorbtion of the oil. Many people put a sealer coat of shellac on before the oil. Please note that this is what I have learned from reading as I have only used Tru oil once on maple and didn't have this problem.
That’s what is strange. It was sealed with shellac after it was stained.Quote:
Originally Posted by Nevin
How are you applying your TO? How long between coats? Are you thinning with mineral spirits (or other)?
I’m applying it by hand. Wipe on. Wipe off. I’m waiting 8 to 12 hours between coats and I haven’t used mineral spirits for thinning.Quote:
Originally Posted by sunburst
From the looks of your picture I think I would let it cure for 24 hours and sand/rub with 1500 grit sandpaper, or with Trizact, or with novus 2 polish, or with whatever smooths it satisfactorily, then begin again with the truoil. Adding a little mineral spirits can make the coats smoother, but build slower.
Thank you, John. I will try that. What do you think caused it to happen. I’m sure it was something I did and I’d like to not do it again.
Did you use dewaxed shellac…if not that could cause finish issues. Only other thought, was it a rainy or humid day when you applied the truoil finish?
I used Zinser blonde shellac. I don’t think it was humidity. I have a humidity controlled room. Generally it’s a consistent 45 to 50% Humidity.Quote:
Originally Posted by john-m
I have used oils and waxes but not on an instrument yet so take this with a grain of salt. I have had that appearance before and it
Was
From applying to thick at one time and not drying well enough between coats. Kind of like a spit shine on my shoes in the Marines. Too much to fast to heavily applied always made a look like that. Thinner coats
with a solid dry worked wonders and a continued hand polish with almost no finish in it to smooth things out. I do not know how well this works on maple.
Zinser sells a shellac sealer that is wax free, as well as dewaxed chips. I may be wrong about this, but I think all the other can shellac products are not dewaxed.
Isn't just a matter of straining the wax out of the shellac? Seems like I did that once a million years ago. I don't remember exactly what I used for straining.
I read something bout separating wax from shellac about a million years ago too. As I remember it there's more to it than simply straining. De-waxed shellac is easy enough to source so I've never tried separating wax from shellac.Quote:
Originally Posted by Dick Hutchings
I forgot to ask the OP how many coats of TO were on the mandolin in the picture. Early coats do look blotchy and the surface improves with subsequent coats. There is always the option of sanding/rubbing between coats if there is a problem (rough place, "goober" or whatever). Through perseverance a TO finish can always be made to look and feel good even if it means starting over. The final surface can be almost anything from a light sheen to nearly full gloss.
To see what a Truoil top coat can look like, check out Kevin Briggs' 2-point threads. That mandolin has a TO over oil varnish finish. It was applied with the 'rub it on, rub it off' method, then hand rubbed with Novus 2 polish.
I have used Tru oil and Tung oil, mostly on custom rifle stocks, but my favorite is Lin-Speed, which is basically, a linseed-based varnish. It goes on very thin, and takes a lot of coats, but seems easier to manage. I have used it on cherry, walnut, and maple. It works well over base coats.
I’m going to get into a lot of trouble from the OSHA guys but I rub it on with my forefinger. I get it even and then let it harden. In Aus it takes 3-4 hours and then I can reapply. I seal with shellac before I start and if need be go to 600grit to get everything smooth before I start with the Tru Oil. 6-8 coats is plenty. A drop does about 2 square inches but i keep rubbing it out till it runs out and feels “dry”.Quote:
Originally Posted by Shawn4390
Then I wash my hands, thoroughly.
Why would you wipe it off? You are trying to build up the finish. It different to Danish oil in that respect.
I've had a similar problem when I used Tru-oil on the edge of rosewood fretboards. The answer was a couple of coats of dewaxed shellac, as previously suggested. I would take note of john-m , and make sure the Zinsser shellac you are using is definitely dewaxed. If not, you have a problem. If it is dewaxed, you could always apply another coat as it is now and then carry on with the truoil. The shellac will sit happily between Tru-oil coats.
That shellac is not dewaxed. Zinnser makes a sanding sealer that is dewaxed. If in the US you might have to get it online. My local stores don't stock it any longer.Quote:
Originally Posted by Shawn4390