lines appearing through painted gyprock?

Originally Posted by bil

Hello We have a small wall (about 2.7 square) and after completing the Gyprock and finishing the joins etc I undercoated and then 3 coats of final (semi-gloss). The lines from the Gyprock join are still there despite it being quite smooth. So now, we are planning on redoing the wall....sanding whole wall, wiping clean, adding more plaster to join and sanding this and then a couple of final coats. Is this the correct procedure? Would appreciate any advice please. Thanks Bil

Any Suggestions please?

Hi Bill, what was your procedure to fill the join? (what materials, trowels, sanding, tape) also what exactly do you mean when you say you can still see the joins?

(Not sure if my earlier reply got through? Shall give it another go) We used the Gyprock joiner (Boral Total Joint Finish) and the three different size plastic trowels. We sanded off between each of the three layers. However, after the undercoat and three final coats one can still see the lines of the join eventhough it feels perfectly smooth. So....we thought we would sand back where the join is (and lightly sand the whole wall)...apply more filler and make it wider this time, then sand etc. We then thought we would use Dulux one Step undercoat? Or? and then two final coats. Any suggestions are very much appreciated. Thanks Bil

Any suggestions?

Originally Posted by Rod Dyson

It is the edge of the rebate showing through. Even though it feels smooth it is not flat. Personally I wouldn't even attempt to do a job with the plastic tools.

To repair just use top coat. You will be able to tell straight away there it is underfilled. It really doesn't take much for the join to show if there is any glancing light on a semi gloss wall. Don't make the mistake of over-filling when doing the fix. You have to let the trowel tell you how much it needs. Unfortunately I don't believe the plastic tools are good enough. Spend $30 on a 12" blade at a plasterboard shop. You will notice the difference.

Good luck with it.

Many thanks for this advice Rod...we appreciate it. Bil

Hi Bill as Rod says only use top coat and get a good quality blade...Topcoat is far finer than base coat, comes pre mixed and sands exceptionally well. When you use the 12" blade don't press too hard as it will cause the blade to flex and you will find it harder. You can pull off the top coat if you press hard and leave marks rather than a super smooth surface. Given it is so easy to sand dont be worried if you get a little too much on as it sands down very quickly.

Top coat is thicker stuff so through working it (usually on a hawk) it becomes a little more user friendly especially if you have not used it before. Working it gets it more malleable and removes trapped air. If you are having problems laying a good 12" wide layer of top coat you can use a smaller blade and do a couple of runs leaving a little more in the center and then go over it with the big 12 incher to finish it all off.

Use a high grit paper in a circular motion only (no back and forth) to sand the next day. If you are seeing swirl marks in the plaster when you sand increase the papers grit to 400 or so..Make sure you have sanded the current surface to give the topcoat something to stick to. Sometimes when you paint with a roller the back and forth rolling action can remove the plaster. It can be microns thick after you have feathered the edges out, so dont go crazy during your initial undercoat.

Good luck. there is nothing more satisfying than standing back and looking at your plastered wall or ceiling and not seeing the joints ) Check Rods videos they are a real help...On utube there are loads however some are bad but the majority are great. Just read the comments as people who know what they are doing will often chirp up and say "your wrong mate!" well far worse but you get the picture.

Thank you very much Grantbudd for your clear advice....it is very helpful. Hopefully, it will do the trick. We appreciate your suggestions...thank you Bil

Dumb question, Did you undercoat the wall before painting?
Without a good seal, top coats will be absorbed at the joins and will be noticeable, especially when side lit (by the sun etc..)

Originally Posted by bil

semi-gloss

This could be your problem. Not forgiving. Try low sheen.